Pressure-induced single-crystal-to-single-crystal nitrite ligand isomerisation accompanied by a piezochromic effect.

High-pressure structural study of a piezochromic crystal of a rare di--nitrito nickel(II) complex supported by computational analysis is presented. The examined system is not photoswitchable, however, in the 0-6.2 GPa pressure range the crystal undergoes two phase-transitions accompanied by a colour change and the nitrite ligand isomerisation, which is unique.

Interrelations between Linkage Isomers of an Efficient Square-planar Nickel(II) Nitrite Photoswitch in the Solid State.

An efficient nitrite nickel(II) photoswitch, with the 1-phenyl-2-hydroxyimino-3-[(2'-dimethylamino)ethyl]imino-1-propanone moiety used as the ancillary ligand, is reported. In the ground-state ('dark') crystal structure, the studied compound exists predominantly as the nitro-(η -N(O) ) isomer, however, traces of the exo- and endo-nitrito-(η -ONO) forms are detected both at 100 K (4-5 % each) and under ambient conditions (~9 % each). When excited with the 405-530 nm LED light, the nitro-to-nitrito isomerization takes place.

Correction: An optically reversible room-temperature solid-state cobalt(III) photoswitch based on nitro-to-nitrito linkage isomerism.

Correction for 'An optically reversible room-temperature solid-state cobalt(III) photoswitch based on nitro-to-nitrito linkage isomerism' by Krystyna A. Deresz , , 2022, , 13439-13442, https://doi.org/10.

An optically reversible room-temperature solid-state cobalt(III) photoswitch based on nitro-to-nitrito linkage isomerism.

A simple trinitro cobalt complex [Co(3,3'-diamino--methylpropanediamine)(NO)] was proven to be photoswitchable at room temperature as the 2 polymorph with the maximum nitro-to-nitrito conversion reaching 55%. Solid-state IR, UV-vis and XRD indicate that the transformation can be triggered optically in both ways 470 nm and 570-660 nm LED light, respectively.

Exploring Photoswitchable Properties of Two Nitro Nickel(II) Complexes with (,,)-Donor Ligands and Their Copper(II) Analogues.

Two photoswitchable nickel(II) nitro coordination compounds and their copper(II) analogues are reported. In all these systems, the metal center is chelated by (,,)-donor ligands containing either 2-picolylamine or 8-aminoquinoline fragments. The studied compounds were thoroughly investigated using crystallographic and spectroscopic techniques supplemented by computational analysis.

Chiral columns forming a lattice with a giant unit cell.

Mesogenic materials, quinoxaline derivatives with semi-flexible cores, are reported to form a new type of 3D columnar phase with a large crystallographic unit cell and lattice below the columnar hexagonal phase. The 3D columnar structure is a result of frustration imposed by the arrangement of helical columns of opposite chiralities into a triangular lattice. The studied materials exhibit fluorescence properties that could be easily tuned by modification of the molecular structure; for compounds with the extended π electron conjugated systems the fluorescence is quenched.

Effect of Diamine Bridge on Reactivity of Tetradentate ONNO Nickel(II) Complexes.

Two new square planar ONNO nickel(II) complexes C2_core and C3_core have been synthesized and characterized by single crystal X-ray diffraction, NMR spectroscopy, thermogravimetry, and DFT calculations. The experimental results revealed the effect of the length of diamine bridge in the ligand on the behavior of the studied complexes in the reaction with N-heterocyclic aromatic amines, while DFT calculations provided a basis for the rationalization of this observation. The complex with propylenediamine bridge (C3_core) readily reacts with pyridine and its derivatives to form high-spin (paramagnetic) complexes with octahedral geometry as characterized by X-ray diffraction; electron-donating substituents on the pyridine ring facilitate the coordination of axial ligands.

Photocrystallographic and spectroscopic studies of a model (N,N,O)-donor square-planar nickel(II) nitro complex: in search of high-conversion and stable photoswitchable materials.

A new, cheap, easy-to-synthesize and air-stable photoswitchable nickel(II) complex, QTNiNO, is reported. The metal centre in QTNiNO is coordinated by a nitro group and a [2-methyl-8-amino-quinoline]-1-tetralone ligand. The compound crystallizes in the tetragonal space group 4/ with one complex molecule comprising the asymmetric unit, and the crystals are stable under ambient conditions.

Calamitic and discotic liquid crystalline phases for mesogens with triangular cores.

Mesogenic compounds having new triangular mesogenic cores containing salicylaldimine and enaminocarbonyl or barbituric moieties have been synthesized and their liquid crystalline, dielectric and optical properties have been studied. Appropriate substitution of such cores with various numbers of lateral chains (alkoxy, perfluorinated or polyether) leads to mesogens forming either lamellar (SmC), nematic or columnar (Colhd and Colho) phases. Some of the materials show an unusual phase sequence with a re-entrant isotropic phase appearing below the columnar (Colhd) phase; others form two columnar hexagonal phases with a weakly first order transition between them.

Fluorescent and charge transport properties of columnar phases made of mono and bi-phenazine derivatives.

Mesogenic dibenzophenazine derivatives have been synthesized and their liquid crystalline, fluorescent and electrochemical properties have been studied. All compounds form the Col phase, one of them (4-hydroxyphenyl 2,3,6,7-tetrakisoctyloxy-dibenzo[a,c]phenazine-11-carboxylate, 4) additionally shows an unusual columnar structure with p2mg symmetry, which is a partially lamellarized columnar phase. The emission spectra exhibit a huge Stokes shift that is due to the different molecular conformation in ground and excited states.

Structural studies of the bond-orientational order and hexatic-smectic transition in liquid crystals of various compositions.

We report on the X-ray studies of freely suspended hexatic films of three different liquid crystal compounds. By applying angular X-ray cross-correlation analysis (XCCA) to the measured diffraction patterns the parameters of the bond-orientational (BO) order in the hexatic phase were directly determined. The temperature evolution of the BO order parameters was analyzed on the basis of the multicritical scaling theory (MCST).

Dinuclear mesogens with antiferromagnetic properties.

Herein, two new groups of isomeric bimetallic nickel(II) and copper(II) complexes containing pyrazine or pyrimidine rings are synthesized and examined. The complexes exhibit liquid-crystalline columnar phases in a broad temperature range. For the copper(II) complexes, super-exchange coupling between two Cu(II) ions is observed.

Structural studies on aryl-substituted enaminoketones and their thio analogues. Part II. Experimental and DFT calculated carbon-carbon coupling constants, (n)J(CC)'s (n = 1-3).

Spin-spin carbon-carbon coupling constants across one, two and three bonds, J(CC), have been measured for a series of aryl-substituted Z-s-Z-s-E enaminoketones and their thio analogues. As a result, a large set, altogether 178, of J(CC)s has been obtained. It consists of 82 couplings across one bond, 31 couplings across two bonds and 65 couplings across three bonds.

Structural studies on aryl-substituted enaminoketones and their thio analogues. Part I. Analysis of high-resolution (1)H, (13)C NMR and (13)C CP MAS spectra combined with GIAO-DFT calculations.

A series of aryl-substituted enaminoketones and their thio analogues in CDCl(3) solution and in the solid state were studied by the use of high-resolution (1)H and (13)C as well as (13)C cross polarization magic angle spinning (CP MAS) NMR spectra in combination with gauge including atomic orbitals-density functional theory (GIAO-DFT) calculations performed at the B3PW91/6-311 + + G(d,p) level of theory using the B3PW91/6-311 + + G(d,p)-optimized geometries. The analysis of the (13)C NMR spectra in solution was done by using the Incredible Natural Abundance DoublE QUAntum Transfer Experiment (INADEQUATE) technique, whereas trends observed in the (13)C shielding constants, calculated for the compounds studied, were a great help in assigning most of the signals in the (13)C CP MAS NMR spectra. It was established on the basis of the experimental and theoretical NMR data that both groups of compounds exist in the form of Z-s-Z-s-E isomers in CDCl(3) solution as well as in the solid state, with the NH hydrogen atom involved in intramolecular hydrogen bonding.

Re-entrant isotropic phase between lamellar and columnar mesophases.

Tetradental cis-enaminoketone Ni (II) complexes with different molecular shape have been synthesized. Intramolecular hydrogen bonds, which stiffen the mesogenic core and restrict rotation of some molecular parts, have been introduced in these compounds. In the case of molecules with two hydrogen bonds and alkoxy terminal chains filling the inner molecular space, the uncommon phase sequence Iso-D(h)-Iso(re)-SmA (series III-3) was detected.

Columnar mesomorphism of bi- and trinuclear Ni(II), Cu(II), and VO(II) cis-enamonoketone complexes with low symmetry.

New enaminoketone tetradentate bi- and trinuclear complexes creating columnar mesophases are reported. Various combinations of nickel, copper, or vanadyl ions were applied as metallic centers. Because of the bowlike structure of chelating centers and the low molecular symmetry (Cs) the bivanadyl complexes form two diastereoisomers, which were separated.