| 1. |
- Abbasi, Alireza, et al.
(författare)
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Ambidentate coordination of dimethyl sulfoxide in rhodium(III) complexes
- 2011
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 40:5, s. 1111-1118
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Tidskriftsartikel (refereegranskat)abstract
- The two dimethyl sulfoxide solvated rhodium(III) compounds, [Rh(dmso-kappa O)(5)(dmso-kappa S)](CF(3)SO(3))(3) (1 & 1* at 298 K and 100 K, respectively) and [Rh(dmso-kappa O)(3)(dmso-kappa S)(2)Cl](CF(3)SO(3))(2) (2), crystallize with orthorhombic unit cells in the space group Pna2(1) (No. 33), Z = 4. In the [Rh(dmso)(6)](3+) complex with slightly distorted octahedral coordination geometry, the Rh-O bond distance is significantly longer with O trans to S, 2.143(6) angstrom (1) and 2.100(6) angstrom (1*), than the mean Rh-O bond distance with O trans to O, 2.019 angstrom (1) and 2.043 angstrom (1*). In the [RhCl(dmso)(5)](3+) complex, the mean Rh-O bond distance with O trans to S, 2.083 angstrom, is slightly longer than that for O trans to Cl, 2.067(4) angstrom, which is consistent with the trans influence DMSO-kappa S > Cl > DMSO-kappa O of the opposite ligands. Raman and IR absorption spectra were recorded and analyzed and a complete assignment of the vibrational bands was achieved with support by force field calculations. An increase in the Rh-O stretching vibrational frequency corresponded to a decreasing trans-influence from the opposite ligand. The Rh-O force constants obtained were correlated with the Rh-O bond lengths, also including previously obtained values for other M(dmso)(6)(3+) complexes with trivalent metal ions. An almost linear correlation was obtained for the MO stretching force constants vs. the reciprocal square of the MO bond lengths. The results show that the metal ion-oxygen bonding of dimethyl sulfoxide ligands is electrostatically dominated in those complexes and that the stretching force constants provide a useful measure of the relative trans-influence of the opposite ligands in hexa-coordinated Rh(III)-complexes.
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| 2. |
- Abbasi, Alireza, et al.
(författare)
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Potassium ion-mediated non-covalent bonded coordination polymers
- 2012
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 41:3, s. 850-859
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Tidskriftsartikel (refereegranskat)abstract
- Crystal structures and vibrational spectra of three related network-forming coordination complexes have been studied. Two novel thermodynamically stable pseudo-polymorphic solvated rhodium chloro compounds, [cis-RhCl4(DMSO-kappa S)(2)K](n), 1, and [cis-RhCl4(DMSO-kappa S)(2)K center dot 3H(2)O](n), 2, and one metastable compound [trans-RhCl4(DMSO-kappa S)(2)K center dot 0.25H(2)O](n), 3, crystallize at ambient temperature in the orthorhombic space group P2(1)2(1)2(1) for 1, and the monoclinic space groups P2(1)/n and P2(1)/c for 2 and 3, respectively. All three structures contain [RhCl4(DMSO-kappa S)(2)]-complexes in which the rhodium(III) ions bind to two dimethyl sulfoxide (DMSO) sulfur atoms and four chloride ions in distorted octahedral coordination geometries. The complexes are connected in networks via potassium ions interacting with the Cl- and the DMSO oxygen atoms. As the sum of Shannon ionic radii of K+ and Cl- exceeds the K-Cl distances in compounds under study, these compounds can be described as Rh-Cl-K coordination polymers with non-covalent bonding, which is not common in these systems, forming 1- and 2-D networks for 1/2 and 3, respectively. The 2-D network with nano-layered sheets for compound 3 was also confirmed by TEM images. Further evaluation of the bonding in the cis- and trans-[RhCl4(DMSO-kappa S)(2)](-) entities was obtained by recording Raman and FT-IR absorption spectra and assigning the vibrational frequencies with the support of force-field calculations. The force field study of complexes reveals the strong domination of trans-effect (DMSO-kappa S > Cl) over the effect of non-covalent bonding in coordination polymeric structures. The comparison of calculated RhCl, RhS and SO stretching force constants showed evidence of K+-ligand interactions whereas direct experimental evidences of K+-Cl- interaction were not obtained because of strong overlap of the corresponding spectral region with that where lattice modes and Rh-ligand bendings appear.
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| 3. |
- Abdel-Magied, Ahmed F., et al.
(författare)
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Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters-diastereomeric control of enantioselectivity
- 2020
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 49:14, s. 4244-4256
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Tidskriftsartikel (refereegranskat)abstract
- Twenty clusters of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P∗)] (P-P∗ = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters. A catalytic mechanism involving an active Ru3 catalyst generated by CO loss from [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P∗)] has been investigated by DFT calculations.
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| 4. |
- Abdelhamid, Hani Nasser, 1986-, et al.
(författare)
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3D printing of cellulose/leaf-like zeolitic imidazolate frameworks (CelloZIF-L) for adsorption of carbon dioxide (CO2) and heavy metal ions
- 2023
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 52:10, s. 2988-2998
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Tidskriftsartikel (refereegranskat)abstract
- Metal–organic frameworks (MOFs) have advanced several technologies. However, it is difficult to market MOFs without processing them into a commercialized structure, causing an unnecessary delay in the material's use. Herein, three-dimensional (3D) printing of cellulose/leaf-like zeolitic imidazolate frameworks (ZIF-L), denoted as CelloZIF-L, is reported via direct ink writing (DIW, robocasting). Formulating CelloZIF-L into 3D objects can dramatically affect the material's properties and, consequently, its adsorption efficiency. The 3D printing process of CelloZIF-L is simple and can be applied via direct printing into a solution of calcium chloride. The synthesis procedure enables the formation of CelloZIF-L with a ZIF content of 84%. 3D printing enables the integration of macroscopic assembly with microscopic properties, i.e., the formation of the hierarchical structure of CelloZIF-L with different shapes, such as cubes and filaments, with 84% loading of ZIF-L. The materials adsorb carbon dioxide (CO2) and heavy metals. 3D CelloZIF-L exhibited a CO2 adsorption capacity of 0.64–1.15 mmol g−1 at 1 bar (0 °C). The materials showed Cu2+ adsorption capacities of 389.8 ± 14–554.8 ± 15 mg g−1. They displayed selectivities of 86.8%, 6.7%, 2.4%, 0.93%, 0.61%, and 0.19% toward Fe3+, Al3+, Co2+, Cu2+, Na+, and Ca2+, respectively. The simple 3D printing procedure and the high adsorption efficiencies reveal the promising potential of our materials for industrial applications.
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| 5. |
- Abdelhamid, Hani Nasser, 1986-
(författare)
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Dye encapsulation and one-pot synthesis of microporous–mesoporous zeolitic imidazolate frameworks for CO2 sorption and adenosine triphosphate biosensing
- 2023
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 52:8, s. 2506-2517
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Tidskriftsartikel (refereegranskat)abstract
- One-pot co-precipitation of target molecules e.g. organic dyes and the synthesis of a crystal containing microporous–mesoporous regimes of zeolitic imidazolate frameworks-8 (ZIF-8) are reported. The synthesis method can be used for cationic (rhodamine B (RhB), methylene blue (MB)), and anionic (methyl blue (MeB)) dyes. The crystal growth of the ZIF-8 crystals takes place via an intermediate phase of zinc hydroxyl nitrate (Zn5(OH)8(NO3)2) nanosheets that enabled the adsorption of the target molecules i.e., RhB, MB, and MeB into their layers. The dye molecules play a role during crystal formation. The successful encapsulation of the dye molecules was proved via diffuse reflectance spectroscopy (DRS) and electrochemical measurements e.g., cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The materials were investigated for carbon dioxide (CO2) adsorption and adenosine triphosphate (ATP) biosensing. ZIF-8, RhB@ZIF-8, MB@ZIF-8, and MeB@ZIF-8 offered CO2 adsorption capacities of 0.80, 0.84, 0.85, and 0.53 mmol g−1, respectively. The encapsulated cationic molecules improved the adsorption performance compared to anionic molecules inside the crystal. The materials were also tested as a fluorescent probe for ATP biosensing. The simple synthesis procedure offered new materials with tunable surface properties and the potential for multi-functional applications.
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| 6. |
- Abernethy, Robyn J., et al.
(författare)
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Relative hemilabilities of H2B(az)2 (az = pyrazolyl, dimethylpyrazolyl, methimazolyl) chelates in the complexes [M(η-C3H5)(CO)2{H2B(az)2}] (M = Mo, W)
- 2020
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 49:3, s. 781-796
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Tidskriftsartikel (refereegranskat)abstract
- The reactions of [M(η3-C3H5)Br(CO)2(NCMe)2] (M = Mo, W) or [Mo(η3-C3H5)Br(CO)2(PMe2Ph)2] with Na[H2B(mt)2] (mt = methimazolyl) affords the complexes [M(η3-C3H5)(CO)2{κ3-H,S,S′-H2B(mt)2}], the 3-centre, 2-electron B-H-M interaction of which was found to be inert with respect to opening under mild conditions, while more forcing conditions (heating with PMe2Ph) resulted in cleavage of the entire allyl and borate ligands to form [Mo(CO)3(PMe2Ph)3]. In contrast, the reaction of [Mo(η3-C3H5)Br(CO)2(NCMe)2] with Na[H2B(pz)2] affords either [Mo(η3-C3H5)(CO)2{κ3-H,N,N′-H2B(pz)2}] or (more likely) [Mo(η3-C3H5)(CO)2(NCMe){κ2-N,N′-H2B(pz)2}] which in turn reacts with phosphines to provide [[Mo(η3-C3H5)(CO)2(PPhR2){κ2-N,N′-H2B(pz)2}] (R = Me, Ph). The reactions discussed indicate the propensity for 3-centre, 2-electron B-H-Mo interactions increases in the order H2B(pz)2 < H2B(pz∗)2 < H2B(mt)2 (pz∗ = 3,5-dimethypyrazolyl).
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| 7. |
- Abrahamsson, Maria, et al.
(författare)
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Microsecond (MLCT)-M-3 excited state lifetimes in bis-tridentate Ru(II)-complexes : significant reductions of non-radiative rate constants
- 2017
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Ingår i: Dalton Transactions. - : ROYAL SOC CHEMISTRY. - 1477-9226 .- 1477-9234. ; 46:39, s. 13314-13321
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we report the photophysical properties of a series of bis-tridentate Ru-II-complexes, based on the dqp-ligand (dqp = 2,6-di(quinolin-8-yl) pyridine), which display several microsecond long excited state lifetimes for triplet metal-to-ligand charge transfer ((MLCT)-M-3) at room temperature. Temperature dependence of the excited state lifetimes for [Ru(dqp)(2)](2+) and [Ru(dqp)(ttpy)](2+) (ttpy = 4'-tolyl-2,2': 6', 2 ''-terpyridine) is reported and radiative and non-radiative rate constants for the whole series are reported and discussed. We can confirm previous assumptions that the near-octahedricity of the bis-dqp complexes dramatically slows down activated decay at room temperature, as compared to most other and less long-lived bis-tridentate RuII-complexes, such as [Ru(tpy)(2)](2+) with tau = 0.25 ns at room temperature (tpy = 2,2': 6', 2 ''-terpyridine). Moreover, the direct non-radiative decay to the ground state is comparatively slow for similar to 700 nm room-temperature emission when considering the energy-gap law. Analysis of the 77 K emission spectra suggests that this effect is not primarily due to smaller excited state distortion than that for comparable complexes. Instead, an analysis of the photophysical parameters suggests a weaker singlet-triplet mixing in the MLCT state, which slows down both radiative and non-radiative decay.
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| 8. |
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| 9. |
- Abu-Youssef, Morsy A.M., et al.
(författare)
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Synthesis, a case of isostructural packing, and antimicrobial activity of silver(I)quinoxaline nitrate, silver(I)(2,5-dimethylpyrazine) nitrate and two related silver aminopyridine compounds
- 2006
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 2006:21, s. 2542-2550
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and low temperature crystal structures of [Ag(quinoxaline)]n(NO3)n, 1, [Ag(2,5-dimethylpyrazine)(NO3)]n, 2 and [Ag4(3-aminopyridine)4(NO3)4]n 3 are presented. The quinoxaline compound forms a 1D coordination polymer with the characteristic linear 2-coordination figure of silver(I), the NAgN angle being 164.2(1)°, and only weak silvernitrate interactions. In addition there is an interaction giving pairs of parallel chains as the main structural theme. The 2,5-dimethylpyrazine compound has approximately trigonal-planar coordination, also binding one nitrate at the relatively short AgO distances 2.444(3)Å and 2.484(3)Å, respectively, for the two crystallographically different silver atoms. This also results in a 1D coordination polymer that, despite the large differences in the Ag(I) coordination environment, is isostructural with 1. [Ag4(3-aminopyridine)4(NO3)4]n 3 forms a 2D coordination polymer by bridging nitrate ions. The antimicrobial activity of 13, and also of [Ag3(2-aminopyridine)4](NO3)3, 4 was screened for 13 different pathogens and substantial activity was shown for 1 against Escherichia coli and Pseudomonas aeruginosa (MIC 4 µg cm3) and somewhat lower activity was registered against Sarcina lutea and Salmonella typhi for 1, Bordetella bronchiseptica for 2, Salmonella typhi and Pseudomonas aeruginosa for 3, and Escherichia coli and Shigella sonnie for 3 (MIC 8 µg cm3). Only low activity was shown against the yeast Candida albicans for 1, 2 and 4 whereas no activity against this pathogen was registered for 3.
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| 10. |
- Adranno, Brando, et al.
(författare)
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Enhanced stability and complex phase behaviour of organic-inorganic green-emitting ionic manganese halides
- 2023
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 52:19, s. 6515-6526
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Tidskriftsartikel (refereegranskat)abstract
- Light-emitting materials based on earth-abundant metals, such as manganese hold great promise as emitters for organic lighting devices. In order to apply such emitter materials and, in particular, to overcome the problem of self-quenching due to cross-relaxation, we investigated a series of tetrabromidomanganate ([MnBr4]2−) salts with bulky tetraalkylphosphonium counter cations [Pnnn]+, namely [Pnnnn]2[MnBr4] (n = 4 (1), 6 (2) and 8 (3)), which can be obtained by a straightforward reaction of the respective phosphonium bromide and MnBr2. Variation of the cation size allows control of the properties of the resulting ionic materials. 1 and 3 qualify as ionic liquids (ILs), where 1 features a melting point of 68 °C, and 3 is liquid at room temperature and even at very low temperatures. Furthermore, 1 and 2 show the formation of higher-ordered thermotropic mesophases. For 1 a transition to a thermodynamically metastable smectic liquid crystalline phase can be observed at room temperature upon reheating from the metastable glassy state; 2 appears to form a plastic crystalline phase at ∼63 °C, which persists up to the melting point of 235 °C. The photoemission is greatly affected by phase behaviour and ion dynamics. A photoluminescence quantum yield of 61% could be achieved, by balancing the increase in Mn2+-Mn2+ separation and reducing self-quenching through increasingly large organic cations which leads to adverse increased vibrational quenching. Compared to analogous ammonium compounds, which have been promoted as @#x0308;inorganic hybrid perovskite, the phosphonium salts show superior performance, with respect to photoluminescent quantum yield and thermal and air/humidity stability. As the presented compounds are not sensitive to the atmosphere, in particular moisture, and show strong visible electroluminescence in the green region of light, they are important emitter materials for use in organic light-emitting devices.
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| 11. |
- Agarwala, Hemlata
(författare)
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Bidirectional non-innocence of the β-diketonato ligand 9-oxidophenalenone (L-) in [Ru([9]aneS3)(L)(dmso)]n, [9]aneS3 = 1,4,7-trithiacyclononane
- 2014
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 43, s. 3939-3948
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Tidskriftsartikel (refereegranskat)abstract
- The new compound [RuII([9]aneS3)(L)(dmso)]ClO4 ([1]ClO4) ([9]aneS3 = 1,4,7-trithiacyclononane, HL =9-hydroxyphenalenone, dmso = dimethylsulfoxide) has been structurally characterised to reveal almostequal C–O bond distances of coordinated L−, suggesting a delocalised bonding situation of the β-diketonatoligand. The dmso ligand is coordinated via the sulfur atom in the native (1+) and reduced states(1 and 1−) as has been revealed by X-ray crystallography and by DFT calculations. Cyclic voltammetry of1+ exhibits two close-lying one-electron oxidation waves at 0.77 V and 0.94 V, and two similarly closeone-electron reduction processes at −1.43 V and −1.56 V versus SCE in CH2Cl2. The electronic structuresof 1n in the accessible redox states have been analysed via experiments (EPR and UV-vis-NIR spectroelectrochemistry)and by DFT/TD-DFT calculations, revealing the potential for bidirectional non-innocent behaviourof coordinated L•/−/•2−. Specifically, the studies establish significant involvement of L basedfrontier orbitals in both the oxidation and reduction processes: [([9]aneS3)(dmso)RuIII–L•]3+ (13+) ⇌ [([9]-aneS3)(dmso)RuIII–L−]2+/[([9]aneS3)(dmso)RuII–L•]2+ (12+) ⇌ [([9]aneS3)(dmso)RuII–L−]+ (1+) ⇌ [([9]aneS3)-(dmso)RuII–L•2−] (1) ⇌ [([9]aneS3)(dmso)RuII–L3−]−/[([9]aneS3)(dmso)RuI–L•2−]− (1−).
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| 12. |
- Agarwala, Hemlata
(författare)
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Electronic structure and catalytic aspects of [Ru(tpm)(bqdi)(Cl/H2O)]n, tpm = tris(1-pyrazolyl)methane and bqdi = o-benzoquinonediimine
- 2013
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 42, s. 3721-3734
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Tidskriftsartikel (refereegranskat)abstract
- The diamagnetic complexes [Ru(tpm)(bqdi)(Cl)]ClO4 ([1]ClO4) (tpm = tris(1-pyrazolyl)methane, bqdi =o-benzoquinonediimine) and [Ru(tpm)(bqdi)(H2O)](ClO4)2 ([2](ClO4)2) have been synthesized. Thevalence state-sensitive bond distances of coordinated bqdi [C–N: 1.311(5)/1.322(5) Å in [1]ClO4;1.316(7)/1.314(7) Å in molecule A and 1.315(6)/1.299(7) Å in molecule B of [2](ClO4)2] imply its fullyoxidised quinonediimine (bqdi0) character. DFT calculations of 1+ confirm the {RuII–bqdi0} versus the antiferromagneticallycoupled {RuIII–bqdi˙−} alternative. The 1H NMR spectra of [1]ClO4 in different solventsshow variations in chemical shift positions of the NH (bqdi) and CH (tpm) proton resonances due to theirdifferent degrees of acidity in different solvents. In CH3CN/0.1 mol dm−3 Et4NClO4, [1]ClO4 undergoesone reversible RuII ⇌ RuIII oxidation and two reductions, the reversible first electron uptake being bqdibased (bqdi0/bqdi˙−). The electrogenerated paramagnetic species {RuIII–bqdi0}(12+) and {RuII–Q˙−}(1)exhibit RuIII-type (12+: = 2.211/Δg = 0.580) and radical-type (1: g = 1.988) EPR signals, respectively, asis confirmed by calculated spin densities (Ru: 0.767 in 12+, bqdi: 0.857 in 1). The aqua complex [2](ClO4)2exhibits two one-electron oxidations at pH = 7, suggesting the formation of {RuIVvO} species. The electronicspectral features of 1n (n = charge associated with the different redox states of the chloro complex:2+, 1+, 0) in CH3CN and of 22+ in H2O have been interpreted based on the TD-DFT calculations. The applicationpotential of the aqua complex 22+ as a pre-catalyst towards the epoxidation of olefins has beenexplored in the presence of the sacrificial oxidant PhI(OAc)2 in CH2Cl2 at 298 K, showing the desiredselectivity with a wide variety of alkenes. DFT calculations based on styrene as the model substratepredict that the epoxidation reaction proceeds through a concerted transition state pathway.IntroductionThe well recognized mixing of ruthenium dπ orbitals andπ orbitals of redox non-innocent quinonoid moieties introducesseveral manifestations with respect to the valence distributionat the metal–quinonoid interface, as depicted in Scheme 1.1This makes the electronic structure of such complexes sensitiveto the molecular frameworks, and in many occasions theexperimental results
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| 13. |
- Agarwala, Hemlata
(författare)
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Electronic structures and selective fluoride sensingfeatures of Os(bpy)2(HL2−) and [{Os(bpy)2}2(μ-HL2−)]2+(H3L: 5-(1H-benzo[d]imidazol-2-yl)-1H-imidazole-4-carboxylic acid)
- 2014
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 43, s. 13932-13947
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Tidskriftsartikel (refereegranskat)abstract
- The article deals with the newly designed mononuclear and asymmetric dinuclear osmium(II) complexesOsII(bpy)2(HL2−) (1) and [(bpy)2OsII(μ-HL2−)OsII(bpy)2](Cl)2 ([2](Cl)2)/[(bpy)2OsII(μ-HL2−)OsII(bpy)2](ClO4)2([2](ClO4)2), respectively, (H3L = 5-(1H-benzo[d]imidazol-2-yl)-1H-imidazole-4-carboxylic acid and bpy = 2,2’-bipyridine). The identity of 1 has been established by its single crystal X-ray structure. The ligand (HL2−)-basedprimary oxidation process (E°298, 0.23 V versus SCE) along with the partial metal contribution (∼20%) in 1 hasbeen revealed by the ligand-dominated HOMO of 1 (HL2−: 88%, Os: 8%), as well as by the Mulliken spindensity distribution of 1+ (HL2−: 0.878, Os: 0.220). Accordingly, 1+ exhibits a free radical type EPR at 77 K witha partial metal-based anisotropic feature (g1 = 2.127, g2 = 2.096, g3 = 2.046; = 2.089; Δg = 0.08).1H-NMR of the dinuclear 22+ in CDCl3 suggests an intimate mixture of two diastereomeric forms in a 1 : 1ratio. The DFT-supported predominantly Os(II)/Os(III)-based couples of asymmetric 22+ at 0.24 V and 0.50 Vversus SCE result in a comproportionation constant (Kc) value of 8.2 × 104. The class I mixed valent state of23+ (S = 1/2) has, however, been corroborated by the Mulliken spin density distribution of Os1: 0.887, Os2:0.005, HL2−: 0.117, as well as by the absence of a low-energy IVCT (intervalence charge transfer) band in thenear-IR region (up to 2000 nm). The appreciable spin accumulation on the bridge in 23+ or 24+ (S = 1, Os1:0.915, Os2: 0.811 and HL2−: 0.275) implies a mixed electronic structural form of [(bpy)2OsIII(μ-HL2−)-OsII(bpy)2]3+(major)/[(bpy)2OsII(μ-HL•−)OsII(bpy)2]3+(minor) or [(bpy)2OsIII(μ-HL2−)OsIII(bpy)2]4+(major)/[(bpy)2-OsIII(μ-HL•−)OsII(bpy)2]4+ (minor), respectively. The mixed valent {OsIII(μ-HL2−)OsII} state in 23+, however, fails toshow EPR at 77 K due to the rapid spin relaxation process. The DFT-supported bpy-based two reductions forboth 1+ and 22+ appear in the potential range of −1.5 V to −1.8 V versus SCE. The electronic transitions in 1nand 2n are assigned by the TD-DFT calculations. Furthermore, the potential anion sensing features of 1 and22+ via the involvement of the available N–H proton in the framework of coordinated HL2− have been evaluatedby different experimental investigations, in conjunction with the DFT calculations, using a wide variety ofanions such as F−, Cl−, Br−, I−, OAc−, SCN−, HSO4− and H2PO4−. This, however, establishes that both 1 and 22+are equally efficient in recognising the F− ion selectively, with log K values of 6.83 and 5.89, respectively.
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| 14. |
- Ahlsten, Nanna, et al.
(författare)
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Allylic alcohols as synthetic enolate equivalents : Isomerisation and tandem reactions catalysed by transition metal complexes
- 2012
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 41:6, s. 1660-1670
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Tidskriftsartikel (refereegranskat)abstract
- Allylic alcohols can be isomerised into carbonyl compounds by transition metal complexes. In the last few years, catalyst design and development have resulted in highly efficient isomerisations under mild reaction conditions, including enantioselective versions. In addition, the isomerisation of allylic alcohols has been combined with C-C bond forming reactions when electrophiles such as aldehydes or imines were present in the reaction mixture. Also, C-F bonds can be formed when electrophilic fluorinating reagents are used. Thus, allylic alcohols can be treated as latent enol(ate)s. In this article, we highlight the latest developments concerning the isomerisation of allylic alcohols into carbonyl compounds, focusing in particular on tandem isomerisation/C-C or C-heteroatom bond formation processes. Significant attention is given to the mechanistic aspects of the reactions.
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| 15. |
- Alammar, Tarek, et al.
(författare)
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Luminescence properties of mechanochemically synthesized lanthanide containing MIL-78 MOFs
- 2018
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 47:22, s. 7594-7601
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Tidskriftsartikel (refereegranskat)abstract
- Three metal-organic framework (MOF) compounds, Ln(0.6) Gd-0.(6) {C6H (COO)(3)); Ln = Eu, Tb, and Dy with a MIL-78 structure, have been synthesized by a solvent-free mechanochemical method from stoichiometric mixtures of benzene 1,3,5-tricarboxylic acid, C6H3 (COOH)(3), also known as trimesic acid, and the respective lanthanide carbonates, Ln(2)(CO3)(3)center dot xH(2)O, Ln = Eu, Gd, Tb and Dy. MIL-78 (Ln(0.5)Gd(0.)(6)) shows the characteristic red, green, and yellow luminescence of Eu3+, Tb3+, and Dy3+, respectively. Efficient intramolecular energy transfer from the ligand triplet state to the excited states of Ln(3+) ions can be observed. The lifetimes and quantum yields of these compounds are studied and discussed in detail. Among the three compounds, the Tb3+ containing compound shows the longest lifetime and highest quantum yield due to a smaller contribution from non-radiative decay pathways and better matching of the lowest triplet energy level of the benzenetricarboxylate ligand and the resonance level of Tb3+.
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| 16. |
- Alavi, Fatemeh Sadat, et al.
(författare)
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A novel mechanism of heme degradation to biliverdin studied by QM/MM and QM calculations
- 2018
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 47:25, s. 8283-8291
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Tidskriftsartikel (refereegranskat)abstract
- Heme degradation by heme oxygenase enzymes is important for maintaining iron homeostasis and prevention of oxidative stress. Previous studies have reported that heme degradation proceeds through three consecutive steps of O2 activation: the regiospecific self-hydroxylation of heme, the conversion of hydroxyheme to verdoheme and CO, and the cleavage of the verdoheme macrocycle to release biliverdin and free ferrous iron. Our results indicate that in the second step of heme degradation, not only verdoheme is generated but ring opening and biliverdin production also occur. We have performed QM-cluster and QM/MM calculations, which show that calculations with H2O as the axial ligand of Fe give the lowest barrier. In the QM-cluster calculation, the reaction is exothermic by -85 kcal mol-1 and the rate-limiting barrier is 5 kcal mol-1, whereas the corresponding QM/MM calculations give a slightly lower barrier of 3 kcal mol-1, owing to strong hydrogen bonds and the protein environment.
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| 17. |
- Ali, Sk Imran, et al.
(författare)
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Antimony oxofluorides - a synthesis concept that yields phase pure samples and single crystals
- 2016
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 45:30, s. 12167-12173
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Tidskriftsartikel (refereegranskat)abstract
- The single crystals of the new isostructural compounds Sb3O4F and Y0.5Sb2.5O4F and the two previously known compounds M-SbOF and alpha-Sb3O2F5 were successfully grown by a hydrothermal technique at 230 degrees C. The new compound Sb3O4F crystallizes in the monoclinic space group P2(1)/c: a = 5.6107(5) angstrom, b = 4.6847(5) angstrom, c = 20.2256(18) angstrom, p = 94.145(8)degrees, z = 4. The replacing part of Sb with Y means a slight increase in the unit cell dimensions. The compounds M-SbOF and alpha-Sb3O2F5 have not been grown as single crystals before and it can be concluded that hydrothermal synthesis has proved to be a suitable technique for growing single crystals of antimony oxofluorides because of the relatively low solubility of such compounds compared to other antimony oxohalides that most often have been synthesised at high temperatures by solid state reactions or gas-solid reactions.
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| 18. |
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| 19. |
- Alshiekh, Alak, et al.
(författare)
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Kinetics of cisplatin binding to short r(GG) containing miRNA mimics - influence of Na(+)versus K(+), temperature and hydrophobicity on reactivity.
- 2015
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; 44:28, s. 12623-12632
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Tidskriftsartikel (refereegranskat)abstract
- Nucleic acids are well recognized targets for platinum-based anticancer drugs, with RNA and DNA being kinetically comparable. In the case of RNA, previous studies have shown that the reaction between small duplex RNAs (dsRNAs) and monoaquated cisplatin (cis-Pt(NH3)2Cl(OH2)(+), ) can be followed by the metal induced hyperchromicity occurring directly after addition of to e.g. microRNA mimics. In the present study, we have used this approach to compare thermal stability and reactivity between intracellularly- and extracellularly relevant salt concentration (CNa(+) and CK(+)ca. 0.1 M), and also as a function of increased hydrophobicity (10% v/v EtOH). In addition, reactivity was studied as a function of temperature in the interval ca. 5-20 °C below the respective dsRNA melting temperatures (Tms). Four different 13- to 20-mer dsRNAs with two different central sequence motifs were used as targets containing either a central r(GG)·r(CC)- or r(GG)·r(UAU)-sequence. The reactions exhibited half-lives in the minute- to hour range at 38 °C in the presence of excess in the μM range. Further, a linear dependence was found between C and the observed pseudo-first-order rate constants. The resulting apparent second-order rate constants were significantly larger for the lower melting r(GG)·r(UAU)-containing sequences compared with that of the fully complementary ones; the higher and lower reactivities represented by RNA-1-3 and RNA-1-1 with k2,appca. 30 and 8 M(-1) s(-1) respectively at CNa(+) = 122 mM. For all RNAs a common small, but significant, trend was observed with increased reactivity in the presence of K(+) compared with Na(+), and decreased reactivity in the presence of EtOH. Finally, the temperature dependence of k2,app was evaluated using the Eyring equation. The retrieved activation parameters reveal positive values for both ΔH(≠) and ΔS(≠) for all dsRNAs, in the range ca. 23-34 kcal mol(-1) and 22-57 cal K(-1) mol(-1) respectively. These values indicate solvational effects to be important for the rate determining step of the reaction, and thus in support of a structural change of the dsRNA to take place in parallel with the adduct formation step.
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| 20. |
- Amenuvor, Gershon, et al.
(författare)
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Novel pyrazolylphosphite- and pyrazolylphosphinite-ruthenium(II) complexes as catalysts for hydrogenation of acetophenone
- 2016
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 45:34, s. 13514-13524
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Tidskriftsartikel (refereegranskat)abstract
- The new compounds and potential ligands 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiphenlyphosphinite (L1), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L2), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl-diethylphosphite (L3) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L4) were prepared from the reaction of (3,5-(disubstituted)pyrazol-1H-yl)ethanol and the appropriate phosphine chloride. The phosphinite (L1) and phosphites (L2-L4) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L5) were reacted with [Ru(p-cymene)Cl2]2 to afford the ruthenium(ii) complexes [Ru(p-cymene)Cl2(L1)] (1), [Ru(p-cymene)Cl2(L2)] (2), [Ru(p-cymene)Cl2(L3)] (3), [Ru(p-cymene)Cl2(L4)] (4), and [Ru(p-cymene)Cl2(L5)] (5). All ruthenium complexes were characterized by a combination of NMR spectroscopy, elemental analysis and, in selected cases, by single crystal X-ray crystallography. Complexes 1-5 and [Ru(p-cymene)Cl2(L6)] (6) (prepared from 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L6)) were investigated as catalysts for both transfer and molecular hydrogenation of acetophenone to 1-phenylethanol. At 80 °C the percent conversion of acetophenone in transfer hydrogenation was moderate to high over 10 h (42-87%); for molecular hydrogenation acetophenone, conversions were as high as 98% in 6 h.
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| 21. |
- Andersson, Claes-Henrik, 1980-, et al.
(författare)
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Synthesis and characterization of a ferrocene-linked bis-fullerene[60] dumbbell
- 2012
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Ingår i: Dalton Transactions. - 1477-9226 .- 1477-9234. ; 41:8, s. 2374-2381
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Tidskriftsartikel (refereegranskat)abstract
- A new [60]fullerene dumbbell consisting of two fulleropyrrolidines connected to a central ferrocene unit by amide linkages has been prepared and fully characterized by elemental analysis, 1H NMR, UV/Vis, fluorescence and mass spectrometry. The electrochemical properties as determined by cyclic voltammetry show ground state electronic communication between the ferrocene and the fullerene units. In addition, the preparaton of a ferrocene building block for an alternative linking approach is presented.
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| 22. |
- Andersson, Ingegärd, et al.
(författare)
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Speciation in the aqueous H+/H2VO4–/H2O2/phosphate system
- 2005
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Ingår i: DALTON TRANSACTIONS. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 22, s. 3658-66
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Tidskriftsartikel (refereegranskat)abstract
- The speciation in the aqueous H+/H2VO4- /phosphate (dihydrogen phosphate, P) and H+/H2VO4/H2O2/P systems has been determined in the physiological medium of 0.150 M Na(Cl) at 25 degrees C. A combination of multinuclear NMR integral and chemical shift (Bruker AMX500) as well as potentiometric data (glass electrode) have been collected and treated simultaneously by the computer program LAKE. The pK(a)-values for phosphoric acid have been determined by potentiometric and P-31 NMR chemical shift data, and have been found to be 1.85 +/- 0.02, 6.69 +/- 0.02 and 11.58 +/- 0.07. The errors given are 3 sigma. Altogether nine vanadate phosphate species have been found in the ternary H+/H2VO4-/P- system in the PH region 1-11, with the following compositions: VP, VP2 and V14P. Equilibrium is very slow in acidic solutions, requiring more than 3 months for the formation of V14P species. On the other hand, less than 15 min are needed for equilibration at neutral and alkaline pH. In the H+/H2VO4-/H2O2/P- system, four new species have been found in addition to all binary and ternary complexes. They are of VXP and VX2P compositions, where X denotes the peroxo ligand. V-51 and P-31 NMR chemical shifts, compositions and formation constants are given, and equilibrium conditions are illustrated in distribution diagrams as well as the fit of the model to the experimental data. Biological and medical relevance of the species is also discussed and physiological conditions are modelled.
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| 23. |
- Andersson, Ingegärd, et al.
(författare)
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Speciation in the aqueous H+/H2VO4–/H2O2/picolinate system relevant to diabetes research
- 2004
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Ingår i: Dalton Transactions. - Cambridge : Royal Society of Chemistry, Thomas Graham House. - 1477-9226 .- 1477-9234. ; :3, s. 421-428
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study of the quaternary aqueous H+/H2VO4−/H2O2/picolinate (Pi−) system has been performed at 25 °C in 0.150 M Na(Cl) medium using quantitative 51V NMR (500 MHz) and potentiometric data (glass electrode). In the ternary H+/H2VO4−/Pi− system, six complexes have been found in the pH region 1–10. In the quaternary H+/H2VO4−/H2O2/Pi−system, eight additional complexes have been found. Generally, equilibria are fast in both systems. The rate of peroxide decomposition depends on the species in solution. Chemical shifts, compositions and formation constants for the species are given. Equilibrium conditions and the fit of the model to the experimental data are illustrated in distribution diagrams. Possible formation of mixed ligand species with imidazole, lactic acid and citric acid have been investigated and ruled out under the same experimental conditions. Structural proposals are given, based on 13C NMR data and available crystal structures.
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| 24. |
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| 25. |
- Arunachalampillai, Athimoolam, et al.
(författare)
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Synthesis and characterisation of PCsp3P phosphine and phosphinite iridium complexes. Cyclometallation and dehydrogenation of a cyclohexyl ring.
- 2009
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; :40, s. 8626-8630
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Tidskriftsartikel (refereegranskat)abstract
- A cyclohexyl based pincer phosphine ligand undergoes cyclometalation with an iridium cyclooctadiene precursor to give a highly thermally stable iridium(III) complex where a C(sp3)-H bond has been oxidatively added. This iridium(III) hydride complex is reduced with potassium to give a terminal iridium(I) dinitrogen complex with no tendency to dimerization. The corresponding cyclohexyl phosphinite ligand undergoes reversible dehydrogenation to give the aromatic cyclometalated iridium(III) hydride complex together with 3 equivalents of dihydrogen.
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