Crystal clear: unveiling giant birefringence in organic-inorganic cocrystals

초록

Coplanar groups with large anisotropic polarizability are suitable as birefringence-active groups for investigating compounds with significant birefringence. In this study, the organic coplanar raw reagent, o-C5H5NO (4HP), was selected as an individual complement. Utilizing the cocrystal engineering strategy, we successfully designed two cocrystals: [LiNO3<middle dot>H2O<middle dot>4HP]<middle dot>4HP (Li-4HP2) and [Mg(NO3)2<middle dot>6H2O]<middle dot>(4HP)2 (Mg-4HP), and one by-product: LiNO3<middle dot>H2O<middle dot>4HP (Li-4HP), which were grown using a mild aqua-solution method. The synergy of the coplanar groups of NO3- and 4HP in the structures resulted in unexpectedly large birefringence values of 0.376-0.522@546 nm. Furthermore, the compounds exhibit large bandgaps (4.08-4.51 eV), short UV cutoff edges (275-278 nm), and favorable growth habits, suggesting their potential as short-wave UV birefringent materials. [LiNO3<middle dot>H2O<middle dot>o-C5H5NO]<middle dot>o-C5H5NO and [Mg(NO3)2<middle dot>6H2O]<middle dot>(o-C5H5NO)2, with giant birefringence, large bandgaps, and good growth habits, were designed using a cocrystal strategy.

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