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In this study, a simple, fast, one-pot approach for the isolation of nanowires (NWs) in coordination chemistry is reported. Nanowires (NWs) of spin-crossover (SCO) materials are extremely rare. Here, an innovative and easy synthetic process was developed to prepare NWs of a switchable polymorph of the known complex trans-[Fe(NCS)2(abpt)2] using a wet-chemistry approach for the first time; abpt is the bidentate chelating ligand 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole. The remarkable smoothness of the high-spin to low-spin transition, monitored through variable-temperature (300-80 K) Raman microscopy, compared with the sharp transition exhibited by the polycrystalline material, demonstrates the effect of the topological properties on the physical phenomena of the system. © 2022 The Royal Society of Chemistry.

The current work reports on a systematic study related to the vibrational modes of the ester carbonyl group in drawn polyesters. We have observed and try to explain how the presence of aromatic units in the molecular structure substantially affects the respective elements of the Raman tensor in contrast to the dipole moment derivative vector which is only marginally influenced. The work is based on the collection of polarized Raman spectra and FTIR dichroism measurements on the one hand and on DFT calculations on the other. The experimental data were obtained from uniaxially stretched aliphatic and semi-aromatic polyesters. The calculations were applied on relevant oriented oligomers and allowed the extraction: (i) of reliable Raman/FTIR vibrational spectra and (ii) the components of the dipole moment derivative and Raman tensor of the vibrational modes and in particular the ones involving the ester carbonyl group. Experimental data indicate that the intensity of the ester carbonyl band is considerably enhanced in the Raman spectra of semi-aromatic polyesters, which results from a considerable enhancement of the related coupling coefficient. Furthermore, the angles of the principle Raman tensor axis are rotated so that the element of the tensor with the greatest value is oriented towards the direction designated by the segment. The latter explains the peculiar experimentally indicated anisotropy, through the ester carbonyl stretching, for the case of semi-aromatic polyesters, which is totally different with that observed in the aliphatic ones. © 2021 Elsevier B.V.

In this study, a simple, fast, one-pot approach for the isolation of nanowires (NWs) in coordination chemistry is reported. Nanowires (NWs) of spin-crossover (SCO) materials are extremely rare. Here, an innovative and easy synthetic process was developed to prepare NWs of a switchable polymorph of the known complex

The current work reports on a systematic study related to the vibrational modes of the ester carbonyl group in drawn polyesters. We have observed and try to explain how the presence of aromatic units in the molecular structure substantially affects the respective elements of the Raman tensor in contrast to the dipole moment derivative vector which is only marginally influenced. The work is based on the collection of polarized Raman spectra and FTIR dichroism measurements on the one hand and on DFT calculations on the other. The experimental data were obtained from uniaxially stretched aliphatic and semi-aromatic polyesters. The calculations were applied on relevant oriented oligomers and allowed the extraction: (i) of reliable Raman/FTIR vibrational spectra and (ii) the components of the dipole moment derivative and Raman tensor of the vibrational modes and in particular the ones involving the ester carbonyl group. Experimental data indicate that the intensity of the ester carbonyl band is considerably enhanced in the Raman spectra of semi-aromatic polyesters, which results from a considerable enhancement of the related coupling coefficient. Furthermore, the angles of the principle Raman tensor axis are rotated so that the element of the tensor with the greatest value is oriented towards the direction designated by the segment. The latter explains the peculiar experimentally indicated anisotropy, through the ester carbonyl stretching, for the case of semi-aromatic polyesters, which is totally different with that observed in the aliphatic ones.

Copyright © 2020 American Chemical Society. We report an investigation of the optical properties, structure, and vibrational modes of SbxAs37-xS48I15 glasses (0 at. % < x < 37 at. %). Optical parameters such as the refractive index, the absorption coefficient, and the optical band gap are correlated with the glass composition. All parameters were found to follow an almost linear dependence with the antimony content x. Both the refractive index and the absorption edge wavelength exhibit a systematic increase against x. Off-resonant Raman spectra of the glasses spectra were measured and analyzed. Structural units, representative of the glass structure, were optimized by density functional theory (DFT) calculations, providing vibrational spectra in agreement with the experiments. Raman spectra were interpreted based on the harmonic frequencies and the activities of vibrational modes obtained by the DFT analysis. The results showed evidence in favor of statistical mixing of iodine atoms, among the various pyramidal units, hence discarding structural models suggesting the presence of isolated pyramidal molecules of the types AsI3/SbI3. Both experimental data and DFT results suggested that iodine atoms exhibit much higher propensity to replace sulfur atoms in antimony than in arsenic-based pyramids. In addition, comparison of experimental and simulated spectra of selected clusters in mixed glasses indicates that it is more probable to find corner-sharing Sb-based pyramids than As-based ones.

The spin-crossover (SCO) polymorph B (complex 1) of the known compound [FeII{N(CN)2}2(abpt)2], where abpt is 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, has been prepared in three different parti...

The synthesis and characterization of the monoanionic heterotrimetallic (d8···d0···d10) complexes [L2Rh(μ-S)2M(μ-S)2CuCl]− (L = P(OPh)3, P(O-o-Tol)3 (P(O-o-CH3C6H4)3), P(OMe)3, P(OEt)3, P(OiPr)3; L2 = COD (1,5-cyclooctadiene), cis-dppen (cis-Ph2PCH = CHPPh2); M = Mo, W) is presented. The complex (NEt4)[(cis-dppen)Rh(μ-S)2W(μ-S)2CuCl] was characterized by X-ray diffraction analysis. The detailed DFT study of the electronic structure of the complexes with P(OMe)3 and COD ligands has revealed the existence of extended electron delocalization over the atom-sharing (spiro) four-membered rings system Rh(μ-S)2M(μ-S)2Cu and the possibility of electronic communication between the terminal metal centers. The electronic spectra of the complexes with P(OMe)3 ligands were studied with TDDFT calculations and the main absorption band in the visible region was assigned to ν(Rh → Mo/W) electron transfer transition. The ν(Rh → Mo/W) transition was found to correlate linearly with Tolman's electronic parameter of the phosphite ligands, making it an electronic parameter for the ligands studied. Finally, the study of the dependence of Δδ(31P) and 1J(Rh-P) of the phosphite complexes, with respect to the QALE model electronic parameters χd, πp and Ear, has succeeded in the assessment of the σ and π effects on these NMR spectral parameters. © 2021

We report an investigation of the optical properties, structure, and vibrational modes of SbxAs37-xS48I15 glasses (0 at. % < x < 37 at. %). Optical parameters such as the refractive index, the absorption coefficient, and the optical band gap are correlated with the glass composition. All parameters were found to follow an almost linear dependence with the antimony content x. Both the refractive index and the absorption edge wavelength exhibit a systematic increase against x. Off-resonant Raman spectra of the glasses spectra were measured and analyzed. Structural units, representative of the glass structure, were optimized by density functional theory (DFT) calculations, providing vibrational spectra in agreement with the experiments. Raman spectra were interpreted based on the harmonic frequencies and the activities of vibrational modes obtained by the DFT analysis. The results showed evidence in favor of statistical mixing of iodine atoms, among the various pyramidal units, hence discarding structural models suggesting the presence of isolated pyramidal molecules of the types AsI3/SbI3. Both experimental data and DFT results suggested that iodine atoms exhibit much higher propensity to replace sulfur atoms in antimony than in arsenic-based pyramids. In addition, comparison of experimental and simulated spectra of selected clusters in mixed glasses indicates that it is more probable to find corner-sharing Sb-based pyramids than As-based ones. Copyright © 2020 American Chemical Society.

The relaxation properties of supercooled AsxS100-x liquids are investigated using a combination of infrared photon correlation spectroscopy and topological constraint theory. Results reveal two channels of relaxation for sulfur-rich compositions that manifest by an unusual profile in the density-density autocorrelation function involving two typical timescales. This indicates a reduced temperature-dependent dynamics for one of the channels associated with a sulfur-rich segregated nanoscale phase that furthermore displays a low liquid fragility. Conversely, the dynamics of the emerging cross-linked As-S network is associated with a growth of the glass transition temperature with As content. These results can be quantitatively understood from topological constraint theory applied to a phase separated network for which a dedicated constraint enumeration must be achieved. The vanishing of this peculiar behavior occurs close to the reported isostatic reversibility window observed at the glass transition. © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.