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N -Monosubstituted ethylenediamine derivatives with three methylene-tethered aromatic groups ((ArCH 2 ) 2 NCH 2 CH 2 N(R)CH 2 Ar (R-ArArAr), where Ar = 2-pyridyl, 2-quinolyl, 1- and 3-isoquinolyl and 2-quinoxalyl; R = methyl, benzyl and phenyl) were utilized as pentadentate ligands for copper(II) complexation. Fifteen mononuclear copper(II) complexes were synthesized and exhibit differences in cyclic voltammetry, absorption spectroscopy and solid state geometries, depending on the aromatic group (Ar) and the substituent on the aliphatic nitrogen atom (R) of the ligand. Compared with the pyridine and isoquinoline complexes, the quinoline and quinoxaline derivatives exhibit distinct Cu(II)/Cu(I) redox potentials and d-d transition absorption wavelengths. Similarly, the phenyl derivatives are different from their methyl and benzyl counterparts. These characteristic trends are discussed in relation to the square-pyramidal/trigonal-bipyramidal structure of the complexes which is perturbed by the location of quinoline moieties in the penta- or hexacoordinate complexes with Jahn-Teller distortion. In addition, the results are compared to the copper(II) complexes with pyridine/quinoline mixed ligands, Ph-Ar1Ar2Ar 3 ((Ar 1 CH 2 )(Ar 2 CH 2 )NCH 2 CH 2 N(Ph)CH 2 Ar 3 ).

Aims: In this study, volatile compounds released from mycelia of some aromatic mushrooms were investigated for their inhibitory activity against plant-pathogenic bacteria and fungi., Methods and Results: A screening revealed that volatile compounds from mycelia of Porostereum spadiceum remarkably inhibited the colony formation of plant-pathogenic bacteria, including Clavibacter michiganensis subsp. michiganensis and Ralstonia solanacearum while also inhibiting the conidial germination of plant-pathogenic fungi including Alternaria brassicicola and Colletotrichum orbiculare. The volatile compounds were isolated from the culture filtrate of P. spadiceum, and 3,4-dichloro-4-methoxybenzaldehyde (DCMB) was identified as a major compound. DCMB significantly inhibited bacterial colonization at 10 μg ml -1 and fungal conidial germination at 0·1-1 μg ml -1 as a vapour., Conclusions: This is the first report on the production of the volatile compound DCMB by P. spadiceum and on the antimicrobial activity of DCMB against plant-pathogenic bacteria and fungi at low concentrations. It may be possible to use the compound as an agent for protecting crops from bacterial and fungal diseases during cultivation and storage., Significance and Impact of the Study: This study provides an understanding of antimicrobial activity of the mushroom volatile compound that may be useful as a novel biological control agent for protecting various plant diseases., (© 2021 The Society for Applied Microbiology.)