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- Kucheriv, Olesia I., et al.
(författare)
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Four‐Step Spin Crossover in a New Cyano‐Bridged Iron‐Silver Coordination Polymer
- 2022
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 28:44
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Tidskriftsartikel (refereegranskat)abstract
- A new guest-free Hofmann clathrate analogue Fe(2-ethoxypyrazine)2{Ag(CN)2}2 which undergoes a four-step spin crossover during the transition from the low-spin to the high-spin state is reported. At the first step 1/3 of centers become high spin, at the second step another 1/3 of centres become high spin, at the third step spin mixed crystallographic centres are observed, and after the fourth step all centers are high spin.
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- Sirenko, Valerii Y., et al.
(författare)
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Nature of cyanoargentate bridges defining spin crossover in new 2D Hofmann clathrate analogues
- 2024
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry. - 1477-9226 .- 1477-9234. ; 53:9, s. 4251-4259
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Tidskriftsartikel (refereegranskat)abstract
- Chemical composition is leading among the numerous factors that determine the spin transition properties of coordination compounds. Classic dicyanometallic bridges {M(CN)2}− are commonly used to build Hofmann-like spin-crossover frameworks, but some extended bridges are also synthetically available. In this paper, we describe a successful synthesis of two very similar spin-crossover frameworks that differ in the cyanometallic bridges involved, namely [Fe(etpz)2{Ag(CN)2}2] (1) and {Fe(etpz)2[Ag2(CN)3][Ag(CN)2]} (2) (where etpz = 2-ethylpyrazine). Magnetic and Mössbauer studies demonstrated the occurrence of abrupt one-step high-spin (HS) ↔ low-spin (LS) transitions for both complexes. The spin transition temperatures are T1/2 ↓ = 233 K and T1/2 ↑ = 243 K for 1 and T1/2 ↓ = 188 K and T1/2 ↑ = 191 K for 2 with thermal hysteresis loops of 10 K for 1 and 3 K for 2. The bridging mononuclear [Ag(CN)2]− units and FeII cations assemble to form infinite 2D layers in the structure of 1. Interestingly, compound 2 forms 2D layers of FeII cations bridged by both binuclear [Ag2(CN)3]− and mononuclear [Ag(CN)2]− units. The structures of 1 and 2 comprise different types of intermolecular interactions including Ag⋯Ag and Ag⋯Netpz, which induce the creation of supramolecular 3D frameworks. The synergy between metallophilic interactions and the spin transition is also confirmed by the variation of Ag⋯Ag distances during spin crossover. The characterization of such analogues allowed us to analyze in detail the effect of the cyanometallic bridge on the structure of new frameworks and on the bistability in Hofmann-like complexes.
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- Sirenko, Y. K., et al.
(författare)
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Compact inhomogeneities in free space : Virtual coordinate boundaries in scalar and vector problems of wave scattering theory
- 2007
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Ingår i: Modeling and Analysis of Transient Processes in Open Resonant Structures. - New York, NY : Springer. - 0387308784 - 9780387308784 ; , s. 69-98
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Bokkapitel (refereegranskat)abstract
- Proceeding with the discussion started in the previous chapters, let us consider model scalar and vector initial boundary value problems typical for the theory of the scattering of transient waves from compact (bounded) inhomogeneities in R2-space (E- and H-polarization) and R3-space. The geometry of the problems (the shape of metal and dielectric inclu sions, the supports of momentary and current sources) may be of a rather general nature. However, it is essential that for all of these geometries there exists a regular region LQ, where the outgoing signal U (g, t) propagates freely. This point is of utmost importance in the algorithms suggested below for truncating the analysis domain.
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- Sirenko, Y. K., et al.
(författare)
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Model synthesis of resonance quasi-optical devices : Dispersive open resonators, absorbing coatings, and pattern-forming structures
- 2007
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Ingår i: Modeling and Analysis of Transient Processes in Open Resonant Structures. - New York, NY : Springer. - 0387308784 - 9780387308784 ; , s. 270-345
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Bokkapitel (refereegranskat)abstract
- Research on resonance wave scattering has made important progress in recent years thanks to a series of profound analytical studies on some general issues and widespread implementation of a new methodology of scientific search based on adequate mathematical modeling and computational experiment. Some physical effects and phenomena discovered and studied in the course of analyzing various resonance structures have become a guide for scientific instrument-making. However, most of the results still remain within the realm of theory. One of the reasons is the complexity of the primary modeling of the problem that should take into account the most complete number of the functionally relevant electromagnetic characteristics of separate elements and allow an estimate of the effectiveness of the system or performance of the device as a whole. As for the resonance quasioptic devices, the problem becomes even more complicated due to the substantial difference (by an order or more) in the characteristic dimensions of the scatterers that jointly create the electromagnetic field with the given parameters.
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- Sirenko, Y. K., et al.
(författare)
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Numerical analysis of transient processes : Fundamental results of the theory, methods, and problems
- 2007
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Ingår i: Modeling and Analysis of Transient Processes in Open Resonant Structures. - New York, NY : Springer. - 0387308784 - 9780387308784 ; , s. 1-37
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Bokkapitel (refereegranskat)abstract
- In this chapter, we describe the state of the art in the development of general approaches and algorithms that serve as bases for solving fundamental and applied problems in the theory of transient electromagnetic fields.
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