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Fotoreaktywność związków heterocyklicznych w warukach zmieniającego się otoczenia chemicznego w świetle chemii obliczeniowej

Janicki Mikołaj J., Szabla Rafał, Góra Robert W.

Wiadomości Chemiczne

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2023

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[Z] 77, 11-12

995--1024

EN

The natural environment and living organisms that surround us are made up of chemical compounds, called chromophores, which can absorb photons coming from UV light from the Sun. The one-photon absorption process leads to ultrafast alteration in the electron density of chromophores, resulting in the population of short-lived excited states. These UV-induced electronic states can be responsible for performing high-energy chemical reactions, which cannot be observed in the chemistry of the ground state. Consequently, photochemical processes could damage the initial structure of a chromophore or allow molecules to undergo the chemical transformation to photoproducts. Therefore, understanding the photochemical and photophysical properties of essential chemical molecules for biology, medicine, renewable energy, and other fieldsis crucial to improve and find applications of light-sensitive systems in daily life. To scrutinize UV-induced chemistry, time-resolved spectroscopy is widely used as an experimental tool to investigate photochemical events. However, the experimental approach cannot provide detailed information about the molecular mechanisms of photochemical processesthat occur in the excited states. Therefore, experimental methods in conjunction with computational photochemistry are used to elucidate the behaviour of UV-excited chemical molecules. Only the synergistic approach can comprehensively describe the photochemical picture of UV-induced molecules. This concise review contains a short introduction to the applications of computational chemistry in the studies of the photochemical properties of chromophores, and major radiationless deactivation pathways occurring in heteroaromatic compounds are briefly discussed. Furthermore, two very recent achievements of joint experimental and theoretical photochemistry studies are outlined, demonstrating how solvent or solute molecules can actively participate in photorelaxation channels of chromophores, allowing for an excited-state intermolecular electron transfer mechanism. The selected and discussed research results show that computational chemistry plays an invaluable role in answering questions about molecular mechanisms in the excited states and enables prediction of unexpected chemical processes.

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Badanie formowania wysokoprądowych obwodów drukowanych z zastosowaniem techniki laserowej

Serzysko T., Borecki J., Grzesiak W.

Elektronika : konstrukcje, technologie, zastosowania

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2017

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Vol. 58, nr 12

39--44

PL

W artykule przedstawiono badanie formowania mozaiki wysokoprądowych obwodów drukowanych poprzez zastosowanie techniki ablacji laserowej miedzi. Łącząc techniki ablacji laserowej z techniką fotochemigrafii przeprowadzono eksperyment mający na celu uzyskanie przekroju formowanej ścieżki o kształcie najbardziej zbliżonym do prostokątnego. Omówiono również możliwość wykonywanie obwodów drukowanych z rozdzielczością sięgającą poziomu 100/100 μm (szerokość ścieżki/odległość izolacyjna między ścieżkami) w warstwie miedzi o grubości 260 μm.

EN

Article presents examination of forming high-current printed circuit board mosaic by the use of copper laser ablation technology. Experiment was conducted by combining laser ablation technology with photochemistry technology. The purpose was to obtain a section of the molded path that is most similar to a rectangular shape. It also discusses the possibility of making printed circuit boards with a resolution of up to 100/100 μm (path width / insulation distance between path) in a copper layer of 260 μm.

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Destrukcja fotochemiczna powierzchni polichromii

Hudziak H., Kubik J.

Roczniki Inżynierii Budowlanej

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2014

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z. 14

27--30

EN

The paper presents the analysis of the polychrome surface changes as a result of photochemical reactions induced by luminous energy flux. After modification of the classical Lambert - Beera formula, for the multiple centre case we obtain an estimation of development of the polychrome surface damage.

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Flavin-related Compounds: 3-Ethyl-lumiflavin. Combined DFT, NMR, X-ray and EI Mass Spectral Study

Sikorska E., Hernando J., Bourdelande J. L., Khmelinskii I., Kubicki M., Komasa A., Prukała D., Sikorski M.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 11

2141-2152

EN

3-Ethyl-lumiflavin was characterized by a variety of methods. Laser flash photolysis measurements in methanol solutions yielded a triplet state living 9.5 ms and a radical species living 91mi s, with steady-state photolysis quantum yields below 10-5. Fluorescence life time of 4.5 ns and quantum yield of 0.16 was recorded in aqueous solu tions. Crystal structure determined by X-ray diffraction was quite similar to the geometry of an isolated molecule calculated using the DFT approach, with the observed differences attributable to a non linear hydrogen bond existing in the crystal solid. EI mass spectra revealed a fragmentation path specific to this compound and in existent in lumiflavin or other similar compounds, due to ejection of a C2H5-N=C=O molecule, containing the ethyl substituent of the parent molecule.

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Osiągnięcia i perspektywy fotochemii stosowanej

Paszyc S.

Przemysł Chemiczny

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2007

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T. 86, nr 9

836-840

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Mathematical model of the bioelectromagnetic field recorded electrographically

Baiculescu S.

Systems Science

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2005

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Vol. 31, no 3

139-144

EN

Recording of the image of the radiating biofield of electrostatic nature on the photosensitive film was made by using an electrographic installation, working under high voltage and low intensity conditions (25-30 kV; 3.5-10 myA), ascending slope monoimpulse, condenser with flat plates, specific cabling. The method initiated by J. Narkevicz (1910), rediscovered by Kirlian (1952), developed by F. Dumitrescu and E. Celan (1975), applied in the study of ontogenesis by C. Guja (1981), used in the experiments on the plant behaviour by M. Godeanu (1983), is presently used in electrographic diagnostics of various medical affections ( Anthropological Research Center of the Romanian Academy) and in some special cognitive experiments (USA, Russia, Germany). The film and electromorphous effects that delimit effluvionary structures with specific density and distribution are generated by the biological field belonging to the surface and inside of the organism. The almost periodical shape of the envelope of the electrographic biological signals (streamers) that belong to the frontier of the palm surface, allowed the determination of its analytical expression, using the theory of aleatory functions, almost periodical in probability. The electrographic results were put into functional connection with neuronal activity, the electroencephalographic signals also having a periodical envelope curve. In the paper, there has been worked out a cybernetic control and regulation diagram of the cerebral waves, using the electrographic-electroencephalographic assembly as well as the medical control unit for cerebral waves by means of luminous signals. The electrographic information was quantified, while the electrographic test was considered an experiment, its results (biological signals) making up an event field with various achievemnt probabilities. The electrographic informational calculation method was applied to some lots with psycho-neuro-endocrine and cardiovascular deseases and to some lots consisting of aging subjects. The comparison was made with the results obtained with the witness lots, introducing the term of compared informational electrography (ClEg). The investigation was made on the palm surface, considering that it best reflects the bioinformational dynamics of the human individual. One may highlight an electrographic informational law, the results being useful for the prospective prefiguration and diagnosing of various affections occuring in some processes specific ofhomeostasis. We determined the mathematical law by means of which its elements are generated; one may attach the human being participating values, corresponding to the hydric, mineral, dielectric, semiconducting components. Isomorphism existing between these components and the biofield forms, recorded electrographically, were highlighted.

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W skorodowanym zwierciadle pamięci. Szkic autobiograficzny

Grabowski Z.R.

Kwartalnik Historii Nauki i Techniki

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2005

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R. 50, nr 2

7--202

PL

Żyłem w ciekawych czasach, przed czym przestrzegał Lejzorek Rojtszwaniec. O najgorszych latach, o latach wojny i okupacji przez blisko pół wieku starałem się zapomnieć. Studiowałem, zostałem chemikiem i w chemii udało mi się zbadać i wyjaśnić kilka zagadek, co przyniosło mi dużą satysfakcję z własnej pracy. Poznałem wielu wybitnych ludzi nauki. Miałem grono serdecznych przyjaciół. Osiągnąłem wszystko, czego człowiek nauki może sobie w Polsce wymarzyć - tytuły, nagrody, medale. Nie zaszkodził mi nawet dość powszechny antysemityzm, którego nieomal nie odczuwałem. W postępowaniu starałem się być uczciwy, w wypowiedziach - szczery; nieraz mi to utrudniało życie1. Ożeniłem się bardzo szczęśliwie - i minęło już półwiecze naszego małżeństwa. Mamy córkę i syna, z których jesteśmy dumni, troje wnuków, w których pokładamy nadzieje. Żyję niespodziewanie długo i dopiero teraz, po pełnym aktywności życiu, powracam pamięcią do przeszłości. Nadszedł czas refleksji.

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Nie kończąca się historia witaminy D

Kroszczyński W., Morzycka B., Morzycki J.W.

Wiadomości Chemiczne

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2002

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[Z] 56, 9-10

793-809

EN

The existence of vitamin D was discovered as a consequence of human disease. Vitamin D deficiency in childhood produces rickets, which is characterized by inadequate calcification of cartilage and bone. In rickets, the whole bony structure is soft and flexible, so that can hardly support the superposed weight of the body. Rickets was common in the 19th century, when the industrial revolution caused change of an agrarian society to an industrial society. The population in large measure spent much more time inside buildings, which shielded them from ultraviolet light. It was proved that sun light and cod liver oil are equally active in preventing and curing rickets. Further studies led to the discovery of an anti-rachitic vitamin D. A deficiency in vitamin D impairs bone formation in growing animals. The precursor of cholecalciferol (vitamin D3) is 7-dehydrocholesterol (provitamin D3) present in the skin. Irradiation of this compound results in the formation of previtamin D3, which spontaneously isomerizes to vitamin D3 (thermal rearrangement). Vitamin D3 is further converted by enzymatic hydroxylation reactions occurring in the liver and kidneys into an active hormone, which was isolated and identified as 1a,25-dihydroxyvitamin D3. Other biologically active metabolites and analogues of vitamin D were also described. The vitamin D endocrine system was primarily recognized for its critical role in calcium and phosphorus homeostasis. The active form of the vitamin, 1a,25-(OH) 2D3, acts on the intestine, bone, and kidney to increase serum levels of these two elements. Receptors for 1a,25-(OH) 2D3 have also been detected in a wide variety of target tissues and cell types, which are not involved in the calcemic activity. The non-classical actions of 1a,25-(OH) 2D3 have suggested a multitude of potential therapeutic applications of the vitamin D hormone for the treatment of hyperproliferative disorders (e.g. cancer and psoriasis), immune dysfunction and endocrine disorders. A number of new drugs based on the vitamin D analogues has been recently introduced to the pharmaceutical market. The story of vitamin D is not finished yet.

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Model studies on the properties of reaction site in hydrophobically modified polymers. I. Effect of cyclodextrins on photochemistry of coumarin 120

Nowakowska M., Smoluch M., Sendor D.

Zeszyty Naukowe. Chemia / Politechnika Śląska

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2001

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z. 146

311-314

EN

The effect of alpha-, beta- and gamma-cyclodextrin, as a model for the hydrophobic reaction sites in microheterogenous polymeric systems, on the photochemical stability of 7-amino-4-methylcoumarin (C 120) was studied. Using spectroscopic techniques combined with HPLC analysis it was demonstrated that addition of beta-cyclodextrin to the aqueous solution of C 120 markedly inhibits the photodegradation of that dye. This was explained by taking into account the possiblity of the formation of an inclusion complex between C 120 and beta-cyclodextrin.

10

pH effects on the photooxidation of methionine derivatives by the 4-carboxybenzophenone triplet state

Hug G., Bobrowski K., Kozubek H., Marciniak B.

Nukleonika

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2000

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Vol. 45, nr 1

63-71

EN

Reduction of the triplet state of 4-carboxybenzophenone (CB) by a series of five substituted methionines was monitored under laser flash photolysis conditions in aqueous solution. Spectral resolution techniques were employed to determine initial quantum yields of the photoproducts. Branching ratios were evaluated for the decay of the charge-transfer complex by the competing processes of back electron transfer, proton transfer, and escape of radical ions. The relative prominence of these processes was discussed in terms of the proton-transfer tendencies of the nominal sulfur-radical-cationic species. A scheme was proposed to account for the pH effects observed. The kinetic equations were solved with a minimum of assumptions, and simulations were performed that qualitatively support the proposed scheme.

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Fotochemia w pracach dawnych badaczy polskich. Cz. 2. Lata 1900-1918

Ruziewicz Z.

Wiadomości Chemiczne

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1998

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[Z] 52, 5-6

325-351

EN

The achievements of Polish scientists are presented against the background of rapid development of photochemistry in the years 1900 - 1918. In organic photochemistry the photohalogenations were the topic of the main interest to many chemists at the universities of Lvov (Bronisław Radziszewski, Stanisław Opolski, Stanisław Tołłoczko) and Cracow (Julian Schramm's folowers). He acenaphthylene photodimerization was discovered in Cracow by Karol Dziewoński in 1912 and the structure of two stereoisomers of the dimer thus obtained was proposed (1913). Contributions of Jan Bielecki, done in Paris (1910-1914), in collaboration with Victor Henri and René Wurmser, are mentioned. Extensive photokinetic studies carried out by Ludwik Bruner at the Jagiellonian University (1907-1913) and the precursory work of Józef Wierusz Kowalski on the phosphorescence spectra of organic molecules, performed in Fribourg (1907-1914), are discussed.