The Structure of Chlorogenic Acid: Spectroscopic and Quanum Mechanical Approach
Struktura hlorogenske kiseline: spektroskopski i kvantno-mehanički pristup
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Author
Tosovic, Jelena
Markovic, Svetlana
Dimitric Markovic, Jasmina
Keywords
MN12-SX functionalvibrational spectra
NMR spectra
UV spectra
vibracioni spektri
NMR spektri
UV spektri
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The aim of this work is to examine the performance of the MN12-SX method to reproduce various spectra of chlorogenic acid (5CQA). The most stable conformers of 5CQA in the gaseous and solvated states were determined. In both conformers the carboxylic hydrogen is not oriented towards the carboxylic oxygen, but towards the adjacent hydroxyl group. This occurrence is a consequence of strong, directed hydrogen bonds in the quinic moiety. MN12-SX shows excellent performance in reproducing the vibrational and NMR specra of 5CQA, but fails in simulating the UV spectrum. This shortcoming of the method can be attributed to neglecting the Hartree-Fock exchange while modeling long-range interactions. Cilj ovog rada je da se ispitaju mogućnosti metode MN12-SX da reprodukuje različite vrste spektara hlorogenske kiseline (5CQA). Određeni su najstabilniji konformeri 5CQA u gasovitoj i solvatisanoj fazi. Karakteristično za oba konformera je to da karboksilni vodoniknije okrenut ka karboksilnom kiseoniku, već ka kiseoniku susedne hidroksilne grupe, što je posledica jakih, usmerenih vodoničnih veza u hininskom delu. MN12-SX odlično reprodukuje vibracione i NMR spektre 5CQA, ali podbacuje u simuliranju UV spektra. Ova mana metode može se pripisati zanemarivanju Hartri-Fokove izmene na velikim međuatomskim rastojanjima.