A triad of two 1,3,5,7-tetramethyl-8-(4-hydroxyphenyl)BODIPY ligands (BODIPY) axially linked to Sn(IV)-octaethylporphyrin [Sn(BODIPY)(2)OEtP] is synthesized. The structure of the triad is optimized by quantum chemical calculations and confirmed by a combination of physicochemical methods. The spectral luminescent properties of the triad and its components in DMF solution are studied. Using a model system of the DMF-glycerol binary solvent, the sensitivity of the photophysical characteristics of the triad to the concentration-dependent viscosity of the solution, as well as to the addition of acids and alkalis, is studied. Sn(BODIPY)(2)OEtP photoexcitation leading to photoinduced energy transfer from donor fragments of BODIPY to the porphyrinate acceptor is observed. As a result, upon excitation of the triad at lambda(ex) = 490 nm both BODIPY fluorescence and porphyrin fluorescence are recorded. When the triad is excited at lambda(ex) = 400 nm, the fluorescence of the porphyrin increases compared to the initial Sn(IV)-octaethylpophyrin. This energy transfer, which depends on both the mobility of the medium and its acidity, provides the Sn(BODIPY)(2)OEtPtriad with the properties of a molecular rotor, a pH indicator and very high photostability (resistance to photobleaching), as well as antibacterial activity against the Staphylococcusaureus ATCC strain.

A triad (Az-SnP-Az) consisting of two azorubine ligands (Az) axially bonded to the sulfo-derivative of Sn (IV)-tetraphenylporphyrin [SnP(OH)2] has been synthesized. The triad structure is optimized by quantum chemical calculations and confirmed by a complex of physicochemical methods. The spectral -luminescent properties of the triad and its components in aqueous media have been studied. The sensi-tivity of the photophysical characteristics of the triad to the concentration-dependent viscosity of the solution has been studied on a model system (binary solvent glycerol-water). It has been established that the resulting triad has the properties of a molecular rotor and exhibits high sensitivity to local viscosity at the Az and SnP absorption maxima. The ability to tune the wavelength of the radiation, allows configur-ing the created "molecular rotor" to monitor the local viscosity for each specific case.(c) 2022 Elsevier B.V. All rights reserved.

The processes of hydrophilic Co(III)-tetra(4-sulfonatophenyl)porphyrin supramolecular assembly with 4,4-bipyridyl in aqueous buffer media have been studied by UV-vis, 1D and 2D 1Н NMR-spectroscopy. In the case of 1,4-diazabicyclo[2.2.2]octane, pyrazine and piperazine in aqueous solutions, no assembly was observed. Interactions of the hydrophilic Co(III)-tetraarylporphyrin with ionic micelles (cationic surfactants with different alkyl tail lengths) in buffer media were investigated. These studies were performed by the UV–vis, 1D NOESY-spectroscopy and dynamic lightscattering (DLS) methods. The metalloporphyrins were incorporated into the hydrophobic part of micelles, which led to Co(III) reduction to Co(II) in the Co-porphyrinate composition. The rate of Co(III) reduction accompanied by detachment of additional ligands coordinated on Co(III)-porphyrins or disruption of supramolecular dimers and depends on the surfactant concentration and nature. The results obtained indicate the possibility of creating of supramolecular porphyrin-based assembles with the preprogrammed lifetime (from several hours to several days) and could be used in the creation of host-guest systems for recognition, selective binding and prolonged release of bioactive substrates as the means in the designing of biomimetic systems with effective binding affinities to heterocycles, DNA base pairs and RNA.

С помощью квантово-химических расчетов на теоретическом уровне DFT/B3LYP/cc-pvTZ изучены процессы транс—цис-изомеризации азобензола (AZB), 4,4'-азопиридина (AZP) и азоксибензола (AZOB). Выбранные объекты могут послужить реперными точками при исследовании внутримолекулярных перегруппировок для множества соединений, содержащих азо- и азоксимостиковую группу. Определены геометрические и электронные характеристики транс- и цис-изомеров AZB и AZP и четырех изомеров AZOB, а также переходных состояний (TS) между ними. Установлено, что два изомера AZOB, содержащие семиполярную связь N→O, обладают значительно более низкой энергией, чем два изомера с мостиковой группой NON циклического строения. Переход между низкоэнергетическими транс—цис-изомерами происходит через TS с сохранением связи N→O без миграции атома кислорода от одного атома азота к другому. Выполнен NBO-анализ электронного строения и отмечены факторы, стабилизирующие полученные геометрические конфигурации всех изомеров и переходных состояний.

Processes of trans–cis isomerization of azobenzene (AZB), 4,4′-azopyridine (AZP), and azoxybenzene (AZOB) are studied using quantum chemical calculations at the DFT/B3LYP/cc-pvTZ level of theory. The chosen objects can serve as reference points when studying intramolecular rearrangements of numerous compounds containing an azo group and an azoxy bridging group. Geometric and electronic characteristics of trans and cis isomers AZB and AZP and four AZOB isomers, as well as transition states (TSs) between them, are determined. It is established that two AZOB isomers containing a semi-polar bond N→O have a significantly lower energy than two isomers with a cyclic NON bridging group. The transition between the low-energy trans–cis isomers proceeds via a TS while preserving the N→O bond so that the oxygen atom does not migrate between the nitrogen atoms. The NBO analysis of the electronic structure is performed, the factors stabilizing the obtained geometric configurations of all isomers and transition states are determined.

The variants of structural organization in the systems “mesogen – nonmesogen” are considered. The systems contain p-n-propyloxycinnamic acid (A), as a mesogenic component, and nonmesogenic Ph–X–Ph compounds: phenyl benzoate (B, where X = –COO–), azobenzene (C, where X = –N=N–) and N-benzylideneaniline (D, where X = –CH=N–). Quantum-chemical modeling of possible structural units in such systems has been performed. It was shown that all assumed A∙∙∙X(Ph)2 H-complexes do not have electronic and geometric anisotropy and have a lower intermolecular interaction energy than the cyclic dimer of acid A∙∙∙A. The calculated values of the Gibbs free energy of complexation reactions also indicate a low probability of the formation of A∙∙∙X(Ph)2 type H-complexes. It is noted that the “length” of the A∙∙∙A dimer is comparable with the doubled “length” of Ph–X–Ph molecules, which, like the acid dimer, have a rod-like structure favorable for the formation of nematic and smectic LC phases. Based on the analysis of the quantum chemical calculations, it was assumed that Ph–X–Ph can be embedded between acid cyclic dimers A∙∙∙A and can facilitate reduce intermolecular interactions in the system, which reduces the temperature of Cr–LC transitions. The proposed structural organization of systems A: Ph–X–Ph is confirmed by an experimental IR spectrum for a similar system, in which the bands corresponding to the vibrational frequencies of the acid dimer and to individual molecules of alkyloxy substituted phenyl benzoate B are recorded.