Diradical Character and Controllable Magnetic Properties in Chitin Through Radical Modification

TS151; The parent and radical-modified chitin units are computationally studied and the parent chitin unit possesses closed-shell singlet ( CS ) state as its ground state. Two radicals ( CH3· and CH3 CH2·) are chosen to modify the parent chitin unit. Calculations predict that CH3 CH2·-modified chitin unit possesses the open-shell broken-symmetry ( BS ) singlet diradical ground state, different from that CH3·-modified chitin unit is a triplet diradical. That is to say, the magnetic conversion can occur from nonmagnetic exchange coupling to antiferromagnetic( AFM) or ferromagnetic( FM) exchange coupling by means of the radical modification method. The present work helps to get a basic understanding of structures and electronic properties of chitin and its radical-modified derivatives at the atomistic level. Moreover, it also provides a feasible way to design new chitin-based magnetic materials and organic magnetic switches.