Sergii S. Smola

Coordination compounds based on CAPh type ligand: synthesis, structural characteristics and luminescence properties of tetrakis-complexes CsLnL4 with dimethylbenzoylamidophosphate

Abstract Searching for prospective luminescent materials, the series of new lanthanide coordination compounds CsLnL4 (Ln = La, Pr, Nd, Sm – Er, and Yb; L− = {C6H5CONPO(OCH3)2}-) was synthesized. X-ray diffraction studies of CsNdL4 and CsYbL4 have been performed establishing polymeric structures of the tetrakis-complexes built from [LnL4]− anions and cesium cations functioning as linkers. The IR, absorption, emission, excitation spectra, and decay time measurements at 298 and 77 K, as well as thermal gravimetric analyses, were used to characterize the complexes.

Effect of esters based on terpenoids and GABA on fluidity of phospholipid membranes

Abstract The influence of esters based on gamma-aminobutyric acid (GABA) and mono-/bicyclic terpenoids on membrane structure was investigated. The mechanism of action for terpenoid esters on phospholipids of artificial membranes and lipids isolated from the rat stratum corneum was studied by fluorescence and FT-IR spectroscopy. We report here, that inclusion of monocyclic terpenoid esters in phospholipid liposomes leads to growth of excimer to monomer ratio (IE/IM) indicating a decrease of membrane microviscosity. Another mechanism of influence on biomembranes was proposed for ester of bicyclic borneol - in this case a high ratio of vibronic peak intensities (I1/I3) was revealed. The addition of terpenoid esters appears in the FT-IR spectra as intensity reduction of absorption bands associated with C = O, P = O and P–O–С groups of lecithin phospholipids. Similar results were obtained after esters addition to lipids isolated from stratum corneum indicating a decrease of hydrogen bonds number between polar groups of lipids. Thus, the influence of terpenoid esters on molecular organization of the lipid matrix substantiates the feasibility of their use after transdermal delivery in vivo.

Luminescence Features of Neodymium(III) Compounds with Various Tetrapyrrole Macrocycles

We considered the changes in the luminescent properties in the series of neodymium(III) complexes of various coordination types with different tetrapyrrole macrocycles (porphyrins, phthalocyanines and corroles): mononuclear complexes (metal-ligand ratio 1:1), sandwich type complexes (metal-ligand ratio 1:2 or 2:3), peripheral binding (on the basis of ditopic tetrapyrrole, metal-ligand ratio 1:1). 4f-Luminescence in the near infrared region is observed in all studied Nd-complexes as a result of intramolecular transfer of excitation energy. Each kind of complexes has its unique features, which are discussed. The peripheral complexes are dual-emissive: they display both neodymium(III) 4f-emission and molecular fluorescence. The values of quantum yield of molecular fluorescence as well as 4f-luminescence are estimated. It was found that binding type plays a key role in excited state relaxation pathways in the molecule. Corroles have unusual behaviour in terms of Nd sensitization.

The Effect of Terpenoid Esters on Membrane Structure Investigated by Fluorescence and Fourier-transform Infrared Spectroscopy

The influence of esters based on gamma-aminobutyric acid (GABA) and mono-/bicyclic terpenoids on membrane structure was investigated. The mechanism of action for terpenoid esters on phospholipids of artificial membranes and lipids isolated from the rat stratum corneum was studied by fluorescence and FT-IR spectroscopy. We report here, that inclusion of monocyclic terpenoid esters in phospholipid liposomes leads to growth of excimer to monomer ratio (IE/IM) indicating a decrease of membrane microviscosity. Another mechanism of influence on biomembranes was proposed for ester of bicyclic borneol ‒ in this case a high ratio of vibronic peak intensities (I1/I3) was revealed. The addition of terpenoid esters appears in the FT-IR spectra as intensity reduction of absorption bands associated with C=O, P=O and Р‒О‒С groups of lecithin phospholipids. Similar results were obtained after esters addition to lipids isolated from stratum corneum indicating a decrease of hydrogen bonds number between polar groups of lipids.

Sol–Gel Organic–Inorganic Hybrid Materials Containing Lanthanide Complexes with Polydentate Acyclic and Cyclic Ligands: Synthesis and Spectral-Luminescent Properties

In this work we report the results of the study on luminescent lanthanide-containing silica-based hybrid materials. The preparation of organic–inorganic hybrids was realized in several stages. At first, the prior modification of the organic ligand (ethylenediaminetetraacetic (EDTA), diethylenetriaminepentaacetic (DTPA) acids, or p-tert-butyl-calix[4]arene (TBC)) with triethoxysylil group was carried out. Then the obtained precursors were reacted with an equimolar amount of lanthanide salt. At last, a sol-gel process was held and organic–inorganic hybrid materials were synthesized. All samples were characterized by elemental analysis, IR-, NMR-spectroscopy, and SEM. Under UV-excitation typical 4f-luminescence was observed in Ln-EDTA-APTMS/SiO2, Ln-DTPA-APTMS/SiO2 and Ln-TBC-TESPIC/SiO2 (Ln = Nd(III), Eu(III), Tb(III), and Yb(III)). The factors determining luminescence efficiency in studied systems are discussed.