Aggregation studies of a photosensitizer (PS), tricationic chlorin (H2Chl3+), and its interaction with passive delivery vehicles Tween 80 and polyvinylpyrrolidone (PVP) in aqueous solutions have been carried out using 1D and 2D NMR spectroscopy, which has been shown to be a powerful tool for detecting both nanoaggregates at about 10–3 mole/kg and associates formed in solutions of H2Chl3+ at PS concentration lower by two orders of magnitude. NMR spectroscopy also can be used to identify molecular fragments of PS responsible for aggregation. The addition of solubilizers Tween 80 and PVP leads to the destruction of the PS nanoaggregates and formation of stable complexes with potential carriers, while the associated forms of the macrocycle may be retained in the solution. These results are consistent with the adsorption, fluorescence, and dynamic light scattering data. The molecular complex of water-soluble H2Chl3+ ions with the PVP macromolecule in aqueous solution is additionally stabilized by hydrogen bonding of the amide NH proton of the photosensitizer and oxygen atom of the polymer carbonyl group.

Методами динамического светорассеяния и электронной спектроскопии поглощения изучены процессы агрегации и дезагрегации моно-, ди- и трикатионного хлоринов (соединения I—III) как потенциальных фотосенсибилизаторов (ФС) для фотодинамической терапии (ФДТ) в воде и водных растворах поливинилпирролидона (ПВП), определен средний размер частиц и характер их распределения. Образование наноагрегатов соединений I—III фиксируется при СФС в интервале 0.7—1.2 ммоль/кг, причем размер частиц увеличивается при хранении раствора. Распределение частиц дисперсной фазы по размерам имеет мономодальный характер только для ФС с более высокой растворимостью в воде. Минимальные добавки ПВП приводят к разрушению крупных (200—300 нм) агрегатов ФС; при этом, согласно спектрам поглощения, агрегаты небольшого размера не разрушаются полностью даже при 100-кратном мольном избытке полимерного ПАВ.

Dynamic light scattering and electron absorption spectroscopy are used to study aggregation and disaggregation of mono-, di-, and tricationic chlorins (compounds I-III) as potential photosensitizers (PSs) for the photodynamic therapy (PDT) in water and aqueous solutions of polyvinylpyrrolidone (PVP). The average particle size and the nature of particle distribution are determined. Nanoaggregate compounds I-III are formed at the CPS values in the interval of 0.7-1.2 mmol/kg, the particle size increases during the storage of the solution. The size distribution of dispersed phase particles is monomodal only for the PSs with high water solubility. According to the absorption spectra, large (200–300 nm) PS aggregates are destroyed as a result of minor PVP additives, whereas small aggregates are not completely destroyed even in the presence of a 100-fold molar excess of the polymer surfactant.

Trends in thermal stability of aromatic macroheterocycles based of pheophorbide a and chlorin e 6 containing hydrophilic groups have been revealed by means of thermogravimetric analysis at 298–1223 K under inert atmosphere. Methylpheophorbide a and 13(1)- N -methylamide of chlorin e 6 are the most stable, the decomposition onset temperature being t o 351 and 333°С. Their functional substitution leads t o the reduction in thermal stability. Depending on the macrocycle structure the decrease in t o can reach 20–200°С.

Spectral (proton magnetic resonance and electronic absorption) parameters of the series of pyro-, meso-, and chlorin derivatives of methylpheophorbide a and kinetics of their complex formation with copper(II) nitrate in organic media have been studied.