Spectroscopy is the study of matter interacting with electromagnetic radiation (e.g., light). The electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR) radiation, microwaves, and radio waves. The frequency (ν) and wavelength (λ) ranges associated with each form of radiant energy are also indicated in Figure 1.

Introduction to Spectroscopy

This work was supported by the Foundation for Science and Technology (FCT), Portugal (projects PTDC/QUI-QUI/113687/2009 and PEst-C/QUI/UI0081/2013). A.G. (SFRH/BD/43531/2008) and M.J.M. (SFRH/BD/61262/2009) thank FCT for grants.

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Chromone: A Valid Scaffold in Medicinal Chemistry

Good Computational Practice in the Assignment of Absolute Configurations by TDDFT Calculations of ECD Spectra.

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=4391&context=smhpapers

A twist of nature--the significance of atropisomers in biological systems.

Neolamarckia cadamba alkaloids as eco-friendly corrosion inhibitors for mild steel in 1 M HCl media

Determination of the absolute configuration (AC) is often a challenging aspect in the structure elucidation of natural products. When chiral compounds possess appropriate chromophore(s), electronic circular dichroism (ECD) may provide a powerful approach to the determination of their absolute configuration. Recently, ECD calculations by time-dependent density functional theory (TDDFT) have come to be used more commonly. In the present review, we give several examples of recent studies using TDDFT-calculated ECD spectra for the AC determination of natural products.

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Circular dichroism calculation for natural products

Two new bisindole alkaloids, bisnicalaterines B and C (1 and 2) consisting of an eburnane and a corynanthe type of skeletons, were isolated from the bark of Hunteria zeylanica. Their absolute structures were determined by combination of NMR, CD, and computational methods, and each of them was shown to be in an atropisomeric relationship. Bisnicalaterines B and C (1 and 2) showed potent vasorelaxant activity on isolated rat aorta.

Bisnicalaterines B and C, Atropisomeric Bisindole Alkaloids from Hunteria zeylanica, Showing Vasorelaxant Activity

A new bisindole alkaloid, bisnicalaterine A (1), consisting of two vobasine-type skeletons, and 3-epivobasinol (2) and 3-O-methylepivobasinol (3), with vobasine-type skeletons, were isolated from the leaves of Hunteria zeylanica, and their structures were elucidated on the basis of spectroscopic data and chemical correlation. Bisnicalaterine A showed moderate cytotoxicity against various human cancer cell lines.

Bisnicalaterine A, a Vobasine-Vobasine Bisindole Alkaloid from Hunteria zeylanica

Leucomidines A-C, novel alkaloids from Leuconotis griffithii

Five new limonoids, ceramicines E—I (1—5), have been isolated from the bark of Chisocheton ceramicus. The structures and relative stereochemistry of them were fully elucidated based on 1D- and 2D-NMR data. Ceramicines E—I (1—5) exhibited moderate cell growth inhibitory activities on a range of cell lines (HL-60, A549, MCF7, and HCT116). The absolute structure of previously isolated ceramicine B (6) was also elucidated by circular dichroism (CD) and X-ray analysis.

Alfarius Eko Nugroho

Papers

Circular dichroism calculation for natural products

Bisnicalaterines B and C, Atropisomeric Bisindole Alkaloids from Hunteria zeylanica, Showing Vasorelaxant Activity

Bisnicalaterine A, a Vobasine-Vobasine Bisindole Alkaloid from Hunteria zeylanica

Leucomidines A-C, novel alkaloids from Leuconotis griffithii

Ceramicines E-I, new limonoids from Chisocheton ceramicus.