| 1. |
- Jain, Titoo, et al.
(författare)
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Additional Article Notification: Anisotropic growth of gold nanoparticles using cationic gemini surfactants: effects of structure variations in head and tail groups
- 2014
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Ingår i: Journal of Materials Chemistry C. - 2050-7534 .- 2050-7526. ; 2:17, s. 3476-3485
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A library of gemini surfactants is employed to study surfactant directed anisotropic growth of gold nanoparticles. The surfactants are modified with respect to the length and type of the tails, as well as of the spacer group. By analyzing the structure of the anisotropic nanoparticles, it is possible to extract information on how the structure of the surfactants influences the anisotropic gold nanocrystal growth. We find that the tail length of the surfactants has a greater influence on the resulting nanoparticle aspect ratio compared to the chemical nature of the spacer group. While clear trends between the aspect ratio and the tail as well as spacer length remain elusive, we observe that surfactants with a critical micelle concentration of similar to 1 mM produce particles with the highest aspect ratio. A crystallographic analysis of nanorods obtained using gemini surfactants reveals that they grow along 100 and are bound by {310} facets. This observation, which is specific for gemini surfactants, is explained by taking into account the preferential alignment of gemini surfactants with surface steps as suggested by electronic structure calculations.
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| 2. |
- Aissaoui, Nesrine, 1983, et al.
(författare)
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FRET enhancement close to gold nanoparticles positioned in DNA origami constructs
- 2017
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Ingår i: Nanoscale. - Cambridge, United Kingdom : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 9:2, s. 673-683
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Tidskriftsartikel (refereegranskat)abstract
- Here we investigate the energy transfer rates of a Förster resonance energy transfer (FRET) pair positioned in close proximity to a 5 nm gold nanoparticle (AuNP) on a DNA origami construct. We study the distance dependence of the FRET rate by varying the location of the donor molecule, D, relative to the AuNP while maintaining a fixed location of the acceptor molecule, A. The presence of the AuNP induces an alteration in the spontaneous emission of the donor (including radiative and non-radiative rates) which is strongly dependent on the distance between the donor and AuNP surface. Simultaneously, the energy transfer rates are enhanced at shorter D-A (and D-AuNP) distances. Overall, in addition to the direct influence of the acceptor and AuNP on the donor decay there is also a significant increase in decay rate not explained by the sum of the two interactions. This leads to enhanced energy transfer between donor and acceptor in the presence of a 5 nm AuNP. We also demonstrate that the transfer rate in the three "particle" geometry (D + A + AuNP) depends approximately linearly on the transfer rate in the donor-AuNP system, suggesting the possibility to control FRET process with electric field induced by 5 nm AuNPs close to the donor fluorophore. It is concluded that DNA origami is a very versatile platform for studying interactions between molecules and plasmonic nanoparticles in general and FRET enhancement in particular.
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| 3. |
- Arroyo, C.R., et al.
(författare)
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Quantum interference effects at room temperature in OPV-based single-molecule junctions
- 2013
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Ingår i: Nanoscale Research Letters. - 1556-276X .- 1931-7573. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Interference effects on charge transport through an individual molecule can lead to a notable modulation and suppression on its conductance. In this letter, we report the observation of quantum interference effects occurring at room temperature in single-molecule junctions based on oligo(3)-phenylenevinylene (OPV3) derivatives, in which the central benzene ring is coupled to either para- or meta-positions. Using the break-junction technique, we find that the conductance for a single meta-OPV3 molecule wired between gold electrodes is one order of magnitude smaller than that of a para-OPV3 molecule. Theoretical calculations confirm the occurrence of constructive and destructive interference in the para- and meta-OPV3 molecules respectively, which arises from the phase difference of the transmission coefficients through the molecular orbitals.
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| 4. |
- Baggi, Nicolò, et al.
(författare)
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Flow-Integrated Preparation of Norbornadiene Precursors for Solar Thermal Energy Storage
- 2024
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Ingår i: ChemSusChem. - 1864-5631 .- 1864-564X. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- Molecular solar thermal (MOST) energy storage systems are getting increased attention related to renewable energy storage applications. Particularly, 2,3-difunctionalized norbornadiene-quadricyclane (NBD-QC) switches bearing a nitrile (CN) group as one of the two substituents are investigated as promising MOST candidates thanks to their high energy storage densities and their red-shifted absorbance. Moreover, such NBD systems can be prepared in large quantities (a requirement for MOST-device applications) in flow through Diels-Alder reaction between cyclopentadiene and appropriately functionalized propynenitriles. However, these acetylene precursors are traditionally prepared in batch from their corresponding acetophenones using reactive chemicals potentially leading to health and physical hazards, especially when working on a several-grams scale. Here, we develop a multistep flow-chemistry route to enhance the production of these crucial precursors. Furthermore, we assess the atom economy (AE) and the E-factor showing improved green metrics compared to classical batch methods. Our results pave the way for a complete flow synthesis of NBDs with a positive impact on green chemistry aspects.
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| 5. |
- Barbosa de Mattos, Deise Fernanda, 1985, et al.
(författare)
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Covalent incorporation of diphenylanthracene in oxotriphenylhexanoate organogels as a quasi-solid photon upconversion matrix
- 2020
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 153:21
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Tidskriftsartikel (refereegranskat)abstract
- Triplet-triplet annihilation photon upconversion (TTA-UC) in solid state assemblies are desirable since they can be easily incorporated into devices such as solar cells, thus utilizing more of the solar spectrum. Realizing this is, however, a significant challenge that must circumvent the need for molecular diffusion, poor exciton migration, and detrimental back energy transfer among other hurdles. Here, we show that the above-mentioned issues can be overcome using the versatile and easily synthesized oxotriphenylhexanoate (OTHO) gelator that allows covalent incorporation of chromophores (or other functional units) at well-defined positions. To study the self-assembly properties as well as its use as a TTA-UC platform, we combine the benchmark couple platinum octaethylporphyrin as a sensitizer and 9,10-diphenylanthracene (DPA) as an annihilator, where DPA is covalently linked to the OTHO gelator at different positions. We show that TTA-UC can be achieved in the chromophore-decorated gels and that the position of attachment affects the photophysical properties as well as triplet energy transfer and triplet-triplet annihilation. This study not only provides proof-of-principle for the covalent approach but also highlights the need for a detailed mechanistic insight into the photophysical processes underpinning solid state TTA-UC.
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| 6. |
- Baronas, Paulius, et al.
(författare)
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Efficient degassing and ppm-level oxygen monitoring flow chemistry system
- 2023
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Ingår i: Reaction Chemistry and Engineering. - 2058-9883. ; 8:8, s. 2052-2059
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Tidskriftsartikel (refereegranskat)abstract
- Low oxygen levels are critical for a long range of chemical transformations carried out in both flow and batch chemistry. Here, we present an inline continuous flow degassing system based on a gas-permeable membrane inside a vacuum chamber for achieving and monitoring ppm-level oxygen concentrations in solutions. The oxygen presence was monitored with a molecular oxygen probe and a continuously running UV-vis spectrometer. An automated setup for discovering optimal reaction conditions for minimal oxygen presence was devised. The parameters tested were: flow rate, vacuum pressure, solvent back-pressure, tube material, tube length and solvent oxygen solubility. The inline degassing system was proven to be effective in removing up to 99.9% of ambient oxygen from solvents at a flow rate of 300 μl min−1 and 4 mbar vacuum pressure inside the degassing chamber. Reaching lower oxygen concentrations was limited by gas permeation in the tubing following the degassing unit, which could be addressed by purging large volume flow reactors with an inert gas after degassing or by using tubing with lower gas permeability, such as stainless steel tubing. Among all factors, oxygen solubility in solvents was found to play a significant role in achieving efficient degassing of solvents. The data presented here can be used to choose optimal experimental parameters for oxygen-sensitive reactions in flow chemistry reaction setups. The data were also fitted to an analytically derived model from simple differential equations in physical context of the experiment.
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| 7. |
- Bertram, Manon, et al.
(författare)
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Norbornadiene photoswitches anchored to well-defined oxide surfaces: From ultrahigh vacuum into the liquid and the electrochemical environment
- 2020
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 152:4
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Tidskriftsartikel (refereegranskat)abstract
- Employing molecular photoswitches, we can combine solar energy conversion, storage, and release in an extremely simple single molecule system. In order to release the stored energy as electricity, the photoswitch has to interact with a semiconducting electrode surface. In this work, we explore a solar-energy-storing model system, consisting of a molecular photoswitch anchored to an atomically defined oxide surface in a liquid electrolyte and under potential control. Previously, this model system has been proven to be operational under ultrahigh vacuum (UHV) conditions. We used the tailor-made norbornadiene derivative 2-cyano-3-(4-carboxyphenyl)norbornadiene (CNBD) and characterized its photochemical and electrochemical properties in an organic electrolyte. Next, we assembled a monolayer of CNBD on a well-ordered Co3O4(111) surface by physical vapor deposition in UHV. This model interface was then transferred into the liquid electrolyte and investigated by photoelectrochemical infrared reflection absorption spectroscopy experiments. We demonstrate that the anchored monolayer of CNBD can be converted photochemically to its energy-rich counterpart 2-cyano-3-(4-carboxyphenyl)quadricyclane (CQC) under potential control. However, the reconversion potential of anchored CQC overlaps with the oxidation and decomposition potential of CNBD, which limits the electrochemically triggered reconversion.
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| 8. |
- Bharmoria, Pankaj, et al.
(författare)
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Far-red triplet sensitized Z-to-E photoswitching of azobenzene in bioplastics
- 2022
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 13, s. 11904-11911
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Tidskriftsartikel (refereegranskat)abstract
- We report the first example of direct far-red triplet sensitized molecular photoswitching in a condensed phase wherein a liquid azobenzene derivative (Azo1) co-assembled within a liquid surfactant-protein film undergoes triplet sensitized Z-to-E photoswitching upon far-red/red light excitation in air. The role of triplet sensitization in photoswitching has been confirmed by quenching of sensitizer phosphorescence by Z-Azo1 and temperature-dependent photoswitching experiments. Herein, we demonstrate new biosustainable fabrication designs to address key challenges in solid-state photoswitching, effectively mitigating chromophore aggregation and requirement of high energy excitations by dispersing the photoswitch in the trapped liquid inside the solid framework and by shifting the action spectrum from blue-green light (450-560 nm) to the far-red/red light (740/640 nm) region.
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| 9. |
- Bharmoria, Pankaj, 1985, et al.
(författare)
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Photon upconverting bioplastics with high efficiency and in-air durability
- 2021
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7534 .- 2050-7526. ; 9:35, s. 11655-11661
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent demand for substituting synthetic plastics to bioplastics for sustainable renewable energy production. Here, we report a simple one-step approach to create bioplastics with efficient and durable photon upconversion (UC) by encapsulating non-volatile chromophore solutions into collagen-based protein films. By just drying an aqueous solution of gelatin, surfactant, and UC chromophores (sensitizer and annihilator), liquid surfactant microdroplets containing the UC chromophores are spontaneously confined within the gelatin films. Thanks to the high fluidity of microdroplets and the good oxygen barrier ability of the collagen-based fiber matrices, a high absolute TTA-UC efficiency of 15.6% and low threshold excitation intensity of 14.0 mW cm−2are obtained even in air. The TTA-UC efficiency was retained up to 8.2% after 2 years of storage under ambient conditions, hence displaying the significant durability desired for practical applications.
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| 10. |
- Bharmoria, Pankaj, 1985, et al.
(författare)
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Protein cohabitation: long-term immunoglobulin G storage at room temperature
- 2023
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Ingår i: Journal of Materials Chemistry B. - : Royal Society of Chemistry. - 2050-750X .- 2050-7518. ; 11:24, s. 5400-5405
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Tidskriftsartikel (refereegranskat)abstract
- Long-term functional storage of therapeutic proteins at room temperature has been an eternal challenge. Inspired by the cellular cooperativity of proteins, we have taken a step forward to address this challenge by cohabitating Immunoglobulin G (IgG1) with a food protein gelatin in the solid-state at room temperature. Interestingly, IgG1 remained functionally active for a record 14 months revealed from the western-blot assay. Further quantification by HP-LC analysis showed 100% structural integrity of IgG1 with no degradation in the gelatin matrix during this period. The developed formulation has a direct application in oral medical nutrition therapy to cure gastrointestinal microbial infections. Also the strategy provides a robust energy economic alternative to the protein engineering methods for long-term functional storage of therapeutic proteins at room temperature.
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