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We present the determination of the conformational properties ofaeroplysinin-1 in aqueous solution by means of a combined experimentaland theoretical Raman optical activity (ROA) and vibrational circulardichroism (VCD) study. Aeroplysinin-1 is an antiangiogenic drug extractedfrom the sponge Aplysina cavernicolawhich has beenproved to be a valuable candidate for the treatment of cancer andother antiangiogenic diseases. Our study shows that this moleculepossesses the 1S,6Rabsolute configurationin aqueous solution, where only two conformers are present to a significantlevel. We discuss in detail the relationships between the chiro-opticalROA and VCD features, and the structural properties of various energyaccessible conformers are described. The present work is one of thefirst studies in which both ROA and VCD have been used as complementarytools for the determination of absolute configuration and dominantsolution-state conformations of an unknown therapeutically significantmolecule. [ABSTRACT FROM AUTHOR]

In this work, the interactions between heteroatoms (S, Se, and Te) and conjugated skeletons are analyzed. The study is carried out by using electronic absorption and fluorescence spectroscopies, electrochemistry, vibrational Raman spectroscopy, and theoretical calculations in the framework of DFT and TD−DFT theories. Optical spectra are described in terms of one-electron promotions between orbitals around the energy gap. Electrochemistry, in the framework of the Koopman's approach, is also interpreted. The vibrational Raman spectra are assigned to molecular modes and the evolution changing the heteroatom is addressed and an effective tuning of these properties is found. Part of this modulation is associated with local electronic interactions depending on the relative S, Se, and Te electronegativities. Unconventional long-range heteroatom−heteroatom interactions have been proposed which arise from the existence of effective π-conjugated channels. The molecular level understanding of structure−property relationships in these organic/inorganic semiconductors are of great interest in the interdisciplinary area of material science. [ABSTRACT FROM AUTHOR]