Conformational studies of bipyrimidine-based mesogens by combination of DFT calculations and temperature-dependent infrared studies

International audienceCombination of DFT calculations and solid-state temperature-dependent infrared spectroscopy has confirmed that the central core of recently developed bipyrimidine-based mesogens is not flat, i.e. do not adopt a disc shape, inside the columnar liquid-crystalline phase. For this purpose, the intensities and the frequency shifts of the most sensitive C–N and C–C bands of the central bipyrimidine core have been studied as a function of the temperature and of the dihedral angle. The results support the reported packing model in which the molecules are interdigitated alternatively along their long axis and their short axis to form columns inside the mesophase

New 2-D silver(I) coordination network constructed from thiomethyl group-substituted p-tert-butylthiacalix[4]arene

International audienceNew ligand based on p-tertbutyltetrathiacalix[4]arene blocked in 1,3-alternate conformation, was achieved via a multistep synthesis with the introduction of thiomethylpropoxy groups on the lower rim which leads to a neutral tecton. The combination of this p-tertbutyltetrathiacalix[4]arene (p-TCA-2), in 1, 3-alternate imposed conformation, with tetrahedral Ag(I)SbF6 salt, leads to the formation of neutral, new 2-D coordination network, which was structurally investigated in the solid state by X-ray diffraction methods on a single crystal

1-D and 2-D coordination networks based on tetrathiacalix[4]arene derivative generated with mercury and cobalt salts

International audienceThe combination of four iso-nicotinate appended tetrathiacalix[4]arene (TCA-1) in 1,2-alternate imposed conformation behaving as neutral tectons with Co(II)Cl(2 )and Hg(II)Cl-2, metallic salts, leads to the formation of neutral, new coordination networks. Indeed, the tetrasubstituted TCA-1 derivative leads to a 1D coordination polymer with Co(II)Cl-2, and a 2D grid-like network with, llg(IDCl2. The effect of the nature of the metal used on the dimensionality was demonstrated by X-ray diffraction studies on a single crystal

Chiral polymorphism in new imine based rod-like liquid crystals

International audienceNew imine based rod-like compounds, composed of three-benzene-ring molecular core linked with azomethine as well as ester groups and terminated with (S)-3,7-dimethyloctyloxy chiral unit at one side have been synthesized. The other terminal position has been varied by using n-octyloxy/decyloxy/dodecyloxy groups to reveal chain length effect on mesophase behavior. The liquid crystalline properties of the new compounds have been investigated by polarizing optical microscopy, differential scanning calorimetry and electro-optic studies. The novel chiral calamitics derived from Schiff base or salicylaldimine-core show a chiral polymorphism comprising of blue phase and chiral nematic as well as smectics such as chiral tilted smectic and unidentified smectic mesophase. (C) 2020 Elsevier B.V. All rights reserved

Pyridine-based chiral smectogens: effects of polar end groups on liquid crystal properties

International audienceIn this study, novel chiral pyridine-based rod-like mesogens, consisting of a chloro or bromo group substituted pyridine head core which is connected to one or two aromatic rings through ester linkers and a flexible (S)-2-methylbutoxy or (S)-3,7-dimethyloctyloxy chiral end chain have been synthesised. The liquid crystal properties of new compounds were investigated by various experimental techniques such as DSC, POM and SAXS. Depending of the nature of the halogen end group, the derivatives with two aromatic rings are non-mesogenic compounds whereas a smectic A phase (SmA) enantiotropically occurs for the members with three aromatic rings of the series. Additionally, chloro group substituted compound composed of three aromatic rings carrying a (S)-2-methylbutoxy end chain exhibits an enantiotropic chiral nematic phase (N*)

Polypyridyl Ruthenium Complexes: Versatile Tools for Linear and Non-Linear Optics

International audienceCoordination complexes have been attracting considerable interest due to their potential nonlinear optical (NLO) properties and applications in optoelectronic and photonic devices. Incorporation of metal atoms into π-conjugated systems allows many variables to be adjusted, such as the nature of ligands and metal ions as well as the symmetry of the complexes. In this paper, new ruthenium(II) complexes of formula [Ru(bpy)2(L)][PF6] and [Ru (L)3][PF6]2 are reported. We studied the influence of the nature of ligands, structural features and symmetry of these complexes on their two-photon absorption properties to provide useful physical and chemical insights for similar ruthenium complexes

Unexpected disruption of the dimensionality-driven two-photon absorption enhancement within a multipolar polypyridyl ruthenium complex series

International audienceThe dimensionality-driven two-photon absorption (2PA) enhancement effect is investigated in a series of functionalized bipyridyl Ru-complexes. Our design strategy leads to very high 2PA responses up to ∼1500 GM. However, we highlight that the 2PA performance vs. dimensionality correlation reaches an unexpected limit stemming from 'anti-cooperative' interchromophoric couplings

Two-Photon Absorption Cooperative Effects within Multi-Dipolar Ruthenium Complexes: The Decisive Influence of Charge Transfers

International audienceOne- and two-photon characterizations of a series of hetero- and homoleptic [RuL(bpy)] ( = 0, 1, 2) complexes carrying bipyridine π-extended ligands (L), have been carried out. These π-extended D-π-A-A-π-D-type ligands (L), where the electron donor units (D) are based on diphenylamine, carbazolyl, or fluorenyl units, have been designed to modulate the conjugation extension and the donating effect. Density functional theory calculations were performed in order to rationalize the observed spectra. Calculations show that the electronic structure of the π-extended ligands has a pronounced effect on the composition of HOMO and LUMO and on the metallic contribution to frontier MOs, resulting in strikingly different nonlinear properties. This work demonstrates that ILCT transitions are the keystone of one- and two-photon absorption bands in the studied systems and reveals how much MLCT and LLCT charge transfers play a decisive role on the two-photon properties of both hetero- and homoleptic ruthenium complexes through cooperative or suppressive effects

Modulation of emission properties of phosphine-sulfonate ligand containing copper complexes playing with solvato-, thermo-, and mechanochromism

International audienceModulations of various neutral phosphine containing copper(i) complexes exhibiting phosphorescence and TADF are easily achieved by solvent modification restricting intramolecular rotation or by modifying the L-X phosphine-sulfonate chelate. This concept is not limited to solvents as the addition of metallic salts also led to the formation of original well-defined photoluminescent K2CuLX3 and KCuL2X2 cuprate complexes