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Subtle structure tailoring of metal-free triazine luminogens for highly efficient ultralong organic phosphorescence
摘要： Highly efficient ultralong organic phosphorescence (UOP) based on a series of metal-free triazine luminogens was achieved via subtly structural tailoring of bromine substituted positions. Impressively, p-BrAT in solid state displayed high phosphorescence efficiency up to 9.7% with a long lifetime of 386 ms, which was one of the highest efficient UOP materials reported so far in metal-free compounds.
关键词： Isomerism,Ultralong organic phosphorescence (UOP),Crystal engineering,H-Aggregation,Intermolecular interactions
更新于2025-09-23 15:23:52
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Distributed polarizability of fullerene [2+1]-adducts C60X (n?=?1 and 2) with symmetric addends?X??=?CH2 and O: A fresh view on the effect of positional isomerism
摘要： We have performed a site-specific analysis of the mean polarizability of fullerene [2+1]-adducts C60Xn (n = 1 and 2) with symmetric addends X = CH2 and O using the distributed polarizability model. We have found that the contributions from the fullerene core and addends to the molecular polarizability are not the same for different regioisomeric C60X2: the core contribution linearly decreases and the addend contribution linearly increases with the distance between the addends (or the functionalized bonds of the C60 cage). Additionally, the contributions are sensible to the degree of the fullerene core functionalization: the contribution of the C60 core decreases with the number of the attached addends due to reducing its π-electronic system.
关键词： isomerism,additive polarizability,polarizability,distributed polarizability,fullerene,fullerene adducts
更新于2025-09-23 15:23:52
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Selectivity, Thermodynamic and Anisotropic Properties of Substituted Liquid-Crystal Cyanoazoxybenzenes as Stationary Phases for Gas Chromatography
摘要： Herein we discuss physical properties of 4-(ω-hydroxyalkoxy)-4’-cyanoazoxybenzene homologs. 1D and 2D correlation NMR spectroscopy (in particular, 1Н, 15N-HMBC experiment) have allowed elucidation of structure of the prepared rod-like supramolecular cyanoazoxybenzenes. Mesomorphic properties of the compounds have been studied by means of polarization thermomicroscopy and differential scanning calorimetry. All the studied cyanoazoxybenzenes have revealed enantiotropic nematic mesomorphism over wide temperature range. Nematic mesophase of the eighth homolog has possessed large positive dielectric anisotropy. Introduction of small amounts of the prepared cyanoazoxybenzenes as additive has stabilized the mesophase and has increased the dielectric anisotropy of 4-pentyloxy-4’-cyanobiphenyl. Gas-liquid chromatography studies have shown that sorbents based on 4-(2-hydroxyethyloxy)-4’-cyanoazoxybenzene are highly selective towards various structural isomers; that cannot be achieved using conventional nematic liquid crystals. Thermodynamic evidence of specific interactions between the mesogen and the non-mesomorphic sorbate has been discovered.
关键词： Mesogen,Dielectric anisotropy,Sorbent,Hydrogen bond,Structural selectivity,NMR spectroscopy,Nematic phase,Position isomerism,Azoxybenzene,Double refraction,Supramolecule
更新于2025-09-19 17:15:36
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Positional Isomerism Controlled Electronic and Photochromic Properties of Naphthalene Diimide-Based Chlorozincate Hybrids
摘要： Two organic-inorganic hybrids, [3-H2DPNDI][ZnCl4]·0.5H2O (1) and [4-H2DPNDI][ZnCl4]·0.5H2O (2) (3-H2DPNDI2+ = protonated N, N-di(3-pyridyl)-1,4,5,8-naphthalene diimide, 4-H2DPNDI2+ = protonated N, N-di(4-pyridyl)-1,4,5,8-naphthalene diimide), have been designed and prepared. Compounds 1 and 2 are constructed from typical [ZnCl4]2- inorganic clusters and positional isomeric organic cations of [H2DPNDI]2+, which are assembled into different 3-D supramolecular networks via different anion-π interactions and hydrogen-bonding interactions. Photochromism of 1 and non-photochromism of 2 are attributable to the usage of positional isomers, which lead to the different spatial stack of [ZnCl4]2- donors and [H2DPNDI]2+ acceptors, suggesting delicate modulating effect of the distinct interfacial contacts on the intermolecular charge transfer/electron transfer and consequently photoresponsive behaviors.
关键词： organic-inorganic hybrids,positional isomerism,anion-π interactions,chlorozincate,photochromism,naphthalene diimide
更新于2025-09-16 10:30:52
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Isomerism and coordination mode effects on two-photon absorption of tris(picolyl)amine-based fluorescent probes for zinc ions
摘要： One-photon absorption and two-photon absorption (TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model. The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer (ICT) properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.
关键词： isomerism,zinc ion,coordination mode,two-photon absorption
更新于2025-09-09 09:28:46
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Photo induced trans→cis isomerism studies of heteroleptic iridium complex with 8-quinolinol-5-phenylazo ligand: Photophysical and electrochemical studies and it's theoretical investigations
摘要： Free rotating azo type ligand in different types of metal complexes give trans-cis isomerism in presence of photon irradiation by UV light. For this connection one new iridium complex has been synthesized with 8-hydroxyquinoline-5-phenylazo ligand in which the azo part of the ligand is free from coordination with metal centre. UV light irradiation of the Ir complex with this type of 8-hydroxyquinoline-5-arylazo ligand at room temperature promotes the trans→cis photoisomerization of the N=N bond with formation of a cis-isomer. The complex is characterised by single X-ray diffractometry, IR, mass and 1HNMR spectroscopy method. Here we report on the synthesis, the electrochemical properties and the photophysical characterization of donor-acceptor azobenzene derivative that possess 8-quinolinol group connected to a benzene moiety and it’s cis-trans isomerisation reaction and stability of the isomers. Thoroughly DFT and TD-DFT calculations are performed to correlate experimental and theoretical interpretation.
关键词： Cis-trans isomerism,Iridium(III) complex,Absorption and emission Study,DFT and TDDFT study
更新于2025-09-04 15:30:14