A new diphenyl ether methyl 2-(2-formyl-3-hydroxy-5-methylphenoxy)-5-hydroxy-3-methoxybenzoate (3), together with four known compounds, asterric acid (1), methyl asterrate (2), 9(Z),12(Z)-nonadecadienoic acid (4) and orsellinic acid (5), were isolated from the Phoma sp. strain SHZK-2, which was isolated from a polluted environment in southern China. The structures of these compounds were determined by spectroscopic methods. Cytotoxicities of compounds against HEPG2 cell and Raji cell lines were preliminarily evaluated by the MTT method.

A series of theoretical methods, including density functional theory, multiconfiguration molecular orbital theory, and ab initio valence bond theory, are devoted to understanding the metal–ligand bonds in M–BP (BP = biphenyl; M = Sc, Y, or La) complexes. Different from most transition metal–BP complexes, the most stable metal–biphenyl conformers are not half-sandwich but clamshell. Energy decomposition analysis results reveal that the M–BP bonds in the clamshell conformers possess extra-large orbital relaxation. According to the wave function analysis, 2-fold donations and 2-fold back-donations exist in the clamshell M–BP bonds. The back-donations from M to BP are quite strong, while donations from BP to M are quite weak. Our work improves our understanding of the metal–ligand bonds, which can be considered as the “reversed” Dewar–Chatt–Duncanson model.

As a monoamine neurotransmitter, serotonin affects a wide range of physiological and behavioral procedures of humans but its biological function is complex and multifaceted. Here we present a comprehensive study of the weak serotoninresidue interactions from cluster science point of view. Eight pairs of serotonin-residue binary clusters are representatively studied. Upon the most stable structures we depict the hydrogen bonding interaction patterns, along with natural bond orbital (NBO) analysis, atoms in molecules (AIM) analysis, generalized Kohn-Sham energy decomposition analysis (GKS-EDA), as well as noncovalent interaction plots based on independent gradient model (IGM). It is found that, for nitrogenous residues, the N⋅⋅⋅HÀ O dominates the noncovalent interactions; while for hydroxyl-containing residues, OÀ H⋅⋅⋅N takes over the dominant interactions; for oxygen and nitrogenfree residues, both electrostatic and VDW-like H-bonds stabilize the binary clusters. This information enriches the molecular mechanism of serotonin receptors and paves a way to study the weak interactions of physiological-active molecules and also supramolecular materials.