Conformation-Dependent Spin Relaxation Behaviors of 6-Oxoverdazyl Radical Single Crystals

The molecular conformation and packing mode of organic radicals are vital to achieving distinctive electronic, spin relaxation, and magnetic properties. Herein two organic radicals, B2P and B4P, are developed by attaching a 6-oxoverdazyl radical at different peripheral positions of [1]­benzothieno­[3,2-b]­[1]­benzothiophene (BTBT). B2P single crystals exhibit a typical herringbone packing mode, whereas B4P single crystals display a classic brick-layer stacking structure. Moreover, two crystalline phases, B4P-Y and B4P-R, are observed in B4P crystals owing to the rotational isomerization. Because of the distinct molecular conformation and packing structures, the spin relaxation behaviors of the two 6-oxoverdazyl radicals are significantly different, and B4P-Y with a distorted conformation exhibits a longer spin relaxation time.