Nodularin time–resolved absorption and resonance FT–IR and raman biospectroscopy and density functional theory (DFT) investigation of vibronic–mode coupling structure in vibrational spectra analysis
Alireza Heidari, Jennifer Esposito, Angela Caissutti
Abstract
Nodularins are potent toxins produced by the cyanobacterium Nodularia spumigena. This aquatic, photosynthetic cyanobacterium forms visible colonies that present as algal blooms in brackish water bodies throughout the world. The late summer blooms of Nodularia spumigena are among the largest cyanobacterial mass occurrences in the world. Cyanobacteria are composed of many toxic substances, most notably of microcystins and nodularins: the two are not easily differentiated. A significant homology of structure and function exists between the two, and microcystins have been studied in greater detail. Because of this, facts from microcystins are often extended to nodularins. Parameters such as FT -IR and Raman vibrational wavelengths and intensities for single crystal Nodularin are calculated using density functional theory and were compared with empirical results. The investigation about vibrational spectrum of cycle dimers in crystal with carboxyl groups from each molecule of acid was shown that it leads to create Hydrogen bonds for adjacent molecules. The current study aimed to investigate the possibility of simulating the empirical values. Analysis of vibrational spectrum of Nodularin is performed based on theoretical simulation and FT-IR empirical spectrum and Raman empirical spectrum using density functional theory in levels of HF/6-31G*, HF/6-31++G**, MP2/6-31G, MP2/6-31++G**, BLYP/6-31G, BLYP/6-31++G**, B3LYP/6-31G and B3LYP6-31-HEG**. Vibration modes of methylene, carboxyl acid and phenyl cycle are separately investigated. The obtained values confirm high accuracy and validity of results obtained from calculations. Molecular structure of Nodularin [1-42]. Heidari A (2019) Nodularin time-resolved absorption and resonance FT-IR and raman biospectroscopy and density functional theory (DFT) investigation of vibronic-mode coupling structure in vibrational spectra analysis Glob Imaging Insights, 2019