Фенолы - потенциальные продукты трансформации фармацевтических загрязнителей - представляют собой угрозу для здоровья человека. В настоящей работе исследуется фототрансформация сульфаметоксазола в воде. Эксперименты по облучению были проведены в условиях стационарного фотореактора с использованием УФ-излучения эксиламп KrCl (l = 222 нм), XeBr(l = 282 нм), XeCl (l = 308 нм) и бактерицидного облучателя ОУФб-04 (l = 180-275 нм). Общее содержание фенолов в фотопродуктах сульфаметоксазола определялось колориметрическим методом с реактивом Фолина-Чокальтеу. Подробно описаны изменения, наблюдаемые в спектрах поглощения и флуоресценции после облучения водных растворов сульфаметоксазола. Показано образование трех флуоресцирующих фотопродуктов, один из которых оказался устойчивым и накапливался в растворе независимо от выбранного источника УФ-излучения. Общее содержание фенолов увеличилось после облучения УФ-источниками. В частности, после 128 мин облучения эксилампой KrClобщее содержание фенолов в четыре раза превысило исходное и составило 331,89 мг GAE/г. Результаты работы могут использоваться при исследовании механизма деградации сульфаниламидов, идентификации токсичных продуктов распада и оценки их антиоксидантной активности. In natural and artificial water bodies, photolysis is the primary process that determines the transformation and fate of many pharmaceuticals. However, there is a lack of information on the degradation products of sulfonamide antibiotics and their toxicity. Phenols are potential transformation products of pharmaceutical contaminants and pose a threat to human health. This paper presents the results of an experimental study of the phototransformation of sulfamethoxazole in water. The irradiation experiments were carried out in a stationary photoreactor using KrCl (222 nm), XeBr (282 nm), and XeCl (308 nm) lamps and a bactericidal irradiator UVb-04 (180-275 nm) as sources of UV radiation. To determine the total phenol content in the photoproducts of sulfamethoxazole, a colorimetric method with Folin-Ciocalteu reagent was used. The changes observed in the absorption and fluorescence spectra after irradiation of aqueous sulfanilamide solutions are described in detail. The formation of three fluorescent photoproducts is shown, one of which is stable and accumulates in the solution regardless of the selected UV radiation source. The total phenol content increased after UV irradiation. It has been established that after 128 min of exposure to a KrCl excimer lamp, the total phenol content is 4 times higher than the initial value and amounts to 331.89 mg GAE/g. The results can be of interest for studying the degradation mechanism of sulfonamides, identifying toxic degradation products, and evaluating their antioxidant activity.

The absorption and fluorescence spectra of sulfaguanidine, its complexes with hydrogen bonds, and doubly charged cationic forms have been studied experimentally and theoretically. The orbital nature of electronically excited states is established and a theoretical interpretation of the absorption and fluorescence spectra is given. It was shown that the main reason for the anomalously large Stokes shift of fluorescence is the rearrangement of the benzoid structure of the phenyl fragment of sulfaguanidine into a quasi-quinoid one. The influence of the formation of hydrogen bonds and the addition of a proton on the amount of charge transfer between weakly bound fragments of the molecule has been established

The absorption spectra of chloramphenicol aqueous solution were obtained experimentally. The absorption spectra of chloramphenicol isomers and the effect on the spectra of the formation of H-bonded complexes were calculated and interpreted using quantum chemistry methods. Calculation results showed that the absorption spectrum of chloramphenicol by position of bands and their nature is largely determined by the nitrobenzene fragment with little participation of propanol and dichloroacetamide fragments of chloramphenicol. The proton acceptor properties of individual chloramphenicol fragments and the effect of the formation of H-bonded complexes on them have been analyzed.

The results of measuring the luminescence of ambient air and solutions of an organic compound during their irradiation with a high-current pulsed electron beam with an average energy of Ee=170 keV and a duration of 2 ns, generated by the RADAN-303 accelerator, are presented. It is shown that, under such exposure, the transformation of dissolved bisphenol A occurs, which is accompanied by an increase in the absorption coefficient of the solution in the wavelength range of more than 300 nm and, as a consequence, a decrease in the intensity of air luminescence bands with an increase in the number of irradiation pulses. The results showed the degradation of the BPA solution to complete decomposition under the action of an electron beam treatment.

The spectral luminescent properties and photolysis of the ionic forms (neutral, cationic and anionic) of bisphenol A have been studied experimentally and by methods of quantum chemistry. Calculations and experiment have shown that, in comparison with a neutral form, no new absorption bands appear in the absorption spectra of ionic form in the range 200–600 nm. The polar solvent (water) shifts the absorption spectrum bands of ionic forms towards low energies. In this case, the shift of the absorption spectrum of the cation is insignificant, and the shift of the anion is significant with an increase in the intensity of the absorption bands. The low quantum yield of fluorescence of ionic form is explained by the prevalence of the efficiency of singlet-triplet conversion over the efficiency of the radiation channel of decay of the fluorescent state. The low quantum yield of fluorescence of the anionic form is due not only to the effective singlet-triplet conversion, but also to the low efficiency of the radiative decay of the fluorescent state of the anion caused by a change in its orbital nature. Calculations have shown that the potential curves of the excited states of bisphenol A and its ionic forms have a significant potential barrier to photolysis. The increase in the efficiency of the process of photodissociation of the bisphenol A anion is caused by a noticeable decrease in the potential barrier and an increase in the overlap of the absorption spectra of the bisphenol A anion and solar radiation.

Методами квантовой химии исследованы спектрально-люминесцентные свойства заряженных (анионной и катионной) форм трех замещенных бензальдегидов, проявляющих биологическую активность: o-анисового (2-метоксибензальдегид) и сиреневого (3,5-диметокси-4-гидроксибензальдегид) бензальдегидов и ванилина (3-метокси-4-гидроксибензальдегид). Расчеты показали, что в случае заряженных форм исследуемых молекул состояние S1 в отличие от нейтральных форм является состоянием ππ*-типа и по своей локализации аналогично S2 (ππ*)-состоянию нейтральных молекул (анисового альдегида и ванилина) или S3 (ππ*)-состоянию сиреневого бензальдегида. По результатам расчета показано, что в области спектра 240-420 nm нет новых электронных переходов, формирующих полосы поглощения в спектре, отличающиеся по природе и локализации от электронных переходов нейтральных молекул. Рассчитанные характеристики флуоресценции заряженных форм исследованных молекул показали, что в отличие от нейтральных форм эффективность радиационного распада заряженных форм много выше, что связано с изменением орбитальной природы состояния S1 при переходе от нейтральной к заряженной форме. Согласно анализу расчетных и экспериментальных данных флуоресценции исследуемых замещенных бензальдегидов в спиртовых растворах, флуоресценция на 410 nm принадлежит катионным формам. В ванилине и сиреневом альдегиде также имеется возможность слабой флуоресценции анионных форм этих соединений. Ключевые слова: замещенные бензальдегиды, спектрально-люминесцентные свойства, методы квантовой химии.

Substituted benzaldehydes widely distributed in nature exhibit antibacterial, anti-inflammatory, antiviral, anti-carcinogenic activity with low toxicity, which make their promising in medicine. The results of an experimental and theoretical study of the spectral-luminescent properties of four neutral forms of hydroxy- and methoxy-substituted benzaldehydes are presented. The absorption spectra of the studied compounds were obtained in hexane and ethanol. Measurements of fluorescence spectra and fluorescence excitation of solutions were carried out in ethanol. Based on quantum chemical calculations, the orbital nature of electronic transitions, the features of the electron density distribution upon excitation and changes in the structure of the compound are determined and the rate constants of photophysical processes are estimated. According to calculations, for all compounds studied, the S1 state is formed by the nπ-type transition, and the intensity of the long-wavelength bands in these compounds is formed by one or two ππ-transitions. The fluorescence quantum yield values are estimated from experimental and theoretical data. As a result of the analysis and comparison of experimental data and the results of quantum chemical calculations it was concluded that the neutral forms of the studied substituted benzaldehydes are not responsible for the observed fluorescence in experiments with ethanol solutions.

The electronic structure and spectral-luminescence properties of the dye merocyanine 540 have been calculated within the framework of the semiempirical quantum-chemical method of partial neglect of differential overlap (PNDO) with spectroscopic parameterization. The trans and cis conformations of the molecule, as well as the trans–cis photoisomerization process, have been considered. The calculation has been performed for an isolated molecule of the merocyanine 540 and its complex with water. The results of the calculation have been compared with the experimental spectral-luminescence characteristics of the molecule in different solvents. It has been shown that there is a good agreement between the calculated and experimental spectra, the nature of the excited states, and photoprocesses.

A mechanism of energy transfer from highly excited triplet aromatic molecules has been developed, which involves a stage of formation of an exciplex between a highly excited energy-donor molecule and an unexcited energy-acceptor molecule. Interpretation of the experimental data on the shape and the intensity of triplet-triplet absorption bands and the energy transfer probability is presented. In this interpretation, the results of quantum-chemical calculations of the energies of highly excited triplet states of toluene and benzene molecules are used.

Изучены спектрально-люминесцентные, генерационные, фотохимические и ресурсные характеристики ряда новых эффективно излучающих дифторборатных комплексов с дипирролилметенами разного строения. Эспериментальные данные получены в полярных и неполярных органических растворителях, а также в твердых полимерных пленках с участием силикатных структур. Обсуждается связь строения исследованных соединений и образованных сольватов с оптическими характеристиками, даны рекомендации по использованию конкретных соединений в качестве активных сред перестраиваемых лазеров для определенных областей спектра.

We have studied the spectroscopic and lasing characteristics of active media based on two synthesized boron fluoride complexes of alkyl-substituted dipyrrolylmethenes and the photostability of the complexes in comparison with complexes of this kind that were previously studied in the literature under identical excitation conditions. We have determined and analyzed conditions under which new compounds have either merits or drawbacks as compared to the known dye with respect to both lasing efficiency and resource characteristics.

The method of intermediate neglect of differential overlap (INDO) with spectroscopic parameterization is used to calculate the electronic structure and the electronically excited states of substituted o-aminophenols comprising the SO2 group. It is demonstrated that incorporation of this group into the 2-anilino-4,6-di-tretbutylphenol molecule leads to separation of the π-systems of phenyl rings forming the molecule. The intramolecular hydrogen bonds of various types and the SO2 group change the charge redistribution between separate fragments of molecules thereby decreasing the donor properties of the phenyl fragments and the acceptor properties of the hydroxyl and amino groups. The influence of the SO2 group on the absorption and fluorescence spectra is insignificant and consists in a small long-wavelength shift of the absorption band spectrum and insignificant changes of the band intensities. Due to a higher degree of deviation of the molecules from the planar structure after incorporation of this group, the intersystem crossing increases; therefore, the quantum fluorescence yield of sulfosubstitutes is insignificant.

Spectra of nonstationary transient absorption of metal bis(dipyrrolylmethene) complexes in cyclohexane and ethanol, which exhibit different photophysical and photochemical properties in these solvents, have been measured and the yields of excited triplet states have been evaluated. It has been shown that the yield of triplets is determined by the intramolecular structure and the difference in fluorescence and phototransformation yields is due to intermolecular interaction of the excited molecules with the solvation shell.

Исследованы спектроскопические и генерационные характеристики активных сред на основе двух синтезированных борфторидных комплексов алкилзамещенных дипирролилметенов и их фотостабильность в сравнении с ранее изученным в литературе комплексом подобного типа в идентичных условиях возбуждения. Найдены и проанализированы условия, при которых новые соединения имеют преимущества либо недостатки по сравнению с известным красителем как по эффективности генерации, так и по ресурсным характеристикам.

The preliminary results of the development and tests of a prototype of a small flow reactor for utilizing stable compounds are presented. A specific feature of the reactor is the use of two excilamps with different radiation wavelengths (λ ∼ 222 nm, λ ∼308 nm) and a polypropylene microfiber material. Then, design of the test bench allows studying the degradation of organic compounds before their mineralization. In accordance with the described technique, the experimental dependences of the decrease in organic compounds on the irradiation time are measured. The energy consumption is within 100 W. The reactor has been developed for training purposes, but it can be used when developing industrial reactors. The proposed design of the reactor equipped with a unit for photocatalytic degradation allows its application for recovery of a wide class of compounds.