The synthesis of new indoline spiropyran by the cyclocondensation in methanol revealed that the free aldehyde group of the target spiropyran is easily converted into the dimethyl acetal moiety ...without the addition of an acid catalyst, giving 8′-dimethoxymethyl-1,3,3-trimethylspiroindoline-2,2′-2
H
-chromene-5,6′-dicarboxylic acid as a single reaction product. The structure of this compound was confirmed by NMR spectroscopy and mass spectrometry. The molecular structure was also established by single-crystal X-ray diffraction. The Hirshfeld surfaces were generated and analyzed and intermolecular interactions in the crystal were investigated using the CrystalExplorer software package. The reverse hydrolysis reaction of dimethyl acetal to the aldehyde group proceeds under mild conditions in dimethyl sulfoxide, as shown by NMR spectroscopy.
The molecular structures and relative energies of stereoisomers of the Co
ɪɪ
and Ni
ɪɪ
bis(chelate) complexes composed of hexa-, penta-, or tetracoordinate metal atoms and (
N, O, O
)-tridentate ...azomethine ligands and having the MN
2
O
2
O
2
, MN
2
O
2
O, and MN
2
O
2
coordination sites, respectively, were obtained from the B3LYP (PBE0, TPSSh)/6-311++G(d,p)) density functional calculations. Simulation of the mechanism of formation of the complexes revealed the energy preferableness of the structures with hexacoordinate central atoms.
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•Spiropyran complexes undergo negative photochromism.•Negative photochromism is quantitatively characterized by the photokinetic method.•Cd2+, Mn2+ and Zn2+ complexes are effective ...photochromic systems.
8-(1,3-Benzoxazol-2-yl) substituted spirobenzopyrans 1A appear as a chromogenic system susceptible of switching between positive and negative photochromism under complexation with metal ions. The thermal and photochemical reactions accompanying metal ion-induced transformation of spiropyrans 1A to the complexes formed by their photoinduced merocyanine isomers 1B were investigated. In the dark, the colorless spiropyrans interact with Mn2+, Cd2+ and Zn2+ transition metal ions to yield deeply colored 1:1 complexes possessing fluorescence, while Co2+, Ni2+, Cu2+ ions prefer to form non-fluorescent complexes with two merocyanines. Under irradiation with visible light solutions of the merocyanine-metal complexes undergo photobleaching. This effect was quantified using photokinetic method.
Stilbene derivatives bearing radical groups in
meta
-positions of phenyl rings were studied in terms of the density functional theory by the M05-2X/6-311++G(d,p) and (B3LYP+D3BJ)/6-311++G(d,p) ...methods. The introduction of bulky paramagnetic substituents is not accompanied by an increase in the energy differences between the isomers. This allows one to expect photoisomerization of the title compounds. Calculations predict very weak exchange interactions between the unpaired electrons of the
trans
- and
cis
- isomers. In the cyclic forms bearing the 1,2,3,5-dithiadiazolyl and 1,5-dimethyl-6-oxoverd-azyl groups the generalized π-system comprising the radicals and the dihydrophenanthrene skeleton provides a strong antiferromagnetic exchange channel, which leads to significant variation of magnetic properties as a result of isomerization.
The reaction of 4,6-di-
tert
-butyl-3-nitrocyclohexa-3,5-diene-1,2-dione with secondary amines (piperidine, morpholine, 1-methylpiperazine) in isopropanol involves Michael addition and ANRORC and ...forms a mixture of products. The resulting compounds were characterized by IR and
1
H and
13
C NMR spectroscopy, and elemental analysis. The molecular structures of 3-nitrocyclohexa-3-ene-1,2-dione and cyclopenta-1,3-diene derivatives were established by X-ray diffraction analysis.
Solid-state photochromic indoline spiropyrans bearing a formyl group at the 6′ and 8′ positions of the 2
H
-chromene moiety of the molecules were characterized. The molecular structures of ...spiropyrans were established by single-crystal X-ray diffraction. Intermolecular interactions and voids in the crystals were investigated using the CrystalExplorer17 software package. Further studies of photochromism and mechanochromism of these spiropyrans in the crystalline state are shown to be promising.
A computer simulation of the structure, energy characteristics, and magnetic properties of mononuclear iron(III) complexes with
N, N
’-substituted 2,11-diaza3.3-(2,6)pyridinophane bases and
o
...-benzoquinone ligands containing nitroxyl and TEMPO radicals was carried out at the UTPSSh/6-311++G(d,p) level of the density functional theory. The dependence of the character of exchange interactions between paramagnetic centers on the nature of the radical group was revealed. It was found that the energy differences between the isomers of compounds studied are determined by the bulkiness of the alkyl substituent at nitrogen atoms of the tetra-azamacrocyclic ligands. Systems potentially capable of manifesting thermally initiated spin crossover were found.
The DFT B3LYP/6-311+G(df,p) and wB97XD/6-311+G(df,p) calculations predict the stability of exohedral complexes of hexaprismanes X
12
H
12
C
n
(X = C, Si, Ge;
n
= 1–3) containing nonclassical carbon ...atoms located at the center of tetragonal faces. On going from the carbon derivatives to the silicon and germanium derivatives the configuration of bonds at the embedded carbon atoms changes from pyramidal to planar and quasi-planar with slight tetrahedral distortion, respectively. The covalent character of the bonds formed by the nonclassical carbon atoms becomes less pronounced on going from the carbon derivatives to the hetero derivatives. The stabilization energies of the complexes increase with increasing the number of embedded carbon atoms. The highest stabilization energies were obtained for the silicon complexes.
The quantum-chemical study of the copper diketonate dimers (Cu(Acac)
2
2
and Cu(Acac)Hfac)
2
) is performed using various functionals (B3LYP, TPSSh, PBE0, and B2PLYP) and basis sets (6-311++G(d,p) ...and Def2-TZVP) and taking into account dispersion interactions (D3BJ). The calculations using the B3LYP and TPSSh functionals combined with the Def2-TZVP basis set give the best agreement with experiment. The Basis Set Superposition Errors introduce no substantial changes to the stabilization energies of the considered systems. The obtained results show that the quantum-chemical study of similar associates of transition metals should be performed without empirical D3BJ dispersion corrections.
