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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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Reakcje [2+4] cykloaddycji cyklopentadienu i furanu z wybranymi β-nitrostyrenami w świetle obliczeń PM3 i PM3/COSMO

Bujak M., Barański A.

Czasopismo Techniczne. Chemia

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2004

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R. 101, z. 1-Ch

13-29

PL

Niniejsza praca dotyczy kwantowochemicznych studiów nad reakcją [2+4] cykloaddycji wybranych β-nitrostyrenów z cyklopentadienem i furanem. Obliczenia prowadzono za pomocą metody PM3 i PM3/COSMO dla fazy gazowej oraz symulowanej obecności medium dielektrycznego.

EN

The PM3 and PM3/COSMO calculations for [2+4] cycloaddition reactions of some β-nitrostyrenes to cyclopentadiene and furane were carried out. Calculations were performed for the gas phase and for dielectric continuum with ε = 2,4 and 37,8.

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Hydratacja kationowych surfaktantów

Zieliński R.

Prace Naukowe Instytutu Technologii Organicznej i Tworzyw Sztucznych Politechniki Wrocławskiej. Konferencje

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2000

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Vol. 48, nr 22

177-180

PL

W pracy przedstawiono struktury molekularne i parametry energetyczne wybranych stabilnych klasterów wodnych utworzonych przez halogenki kilku szeregów homologicznych kationowych surfaktantów. Na podstawie przeprowadzonych obliczeń semiempirycznych stwierdzono, że minimalna liczba cząsteczek wody wymagana do utworzenia trwałego klasteru wodnego kationowego surfaktanta wynosi trzy. Znaleziono liniowe korelacje pomiędzy obliczonymi wartościami energii tworzenia tych klasterów a doświadczalnymi wartościami entalpii swobodnej procesu tworzenia się micel w wodnych roztworach kationowych surfaktantów

EN

Molecular structures and energetical parameters of selected stable water clusters formed by of several salts of cationic surfactants are presented. Based on semiempirical computations carried out for the clusters it was found that at least three water molecules are necessary to form a stable water cluster of cationic surfactant. Good linear correlations have been found between computed values of the heat of formation of the clusters and experimental values of the free energy of micelle formation in aqueous solutions of cationic surfactants.