Conducting 2D Nanosheets: Photo Driven Crystallinity in Self-Assembled Cu (II) Metalated Porphyrin-Bispyridylquinoxaline

Abstract

Tuning the crystallinity in self-assembled nanostructures has a significant impact on the electronic properties. Although several approaches have been adopted for organic π-conjugated systems to generate the amorphous to crystalline structures, the bulky structure of extended macrocyclics is hitherto unknown. Herein, we have developed three symmetric freebase and metallo substituted porphyrin appended bispyridylquinoxalines (PFb-DPQ, PCu-DPQ and PZn-DPQ) in which copper metalated P-DPQ exhibits crystalline phase transitions under light stimuli. Notably, light irradiated P-DPQ derivatives undergo a protonation, demetalation, and anion binding mechanism, resulting in the formation of self-assembled open, closed 0D nanospheres together with 2D nanosheets via methanol vapor diffusion approach. Interestingly, light stimulation regulates the morphology from 0D nanosphere to 2D nanosheets in PCu-DPQ and H+[PCu-DPQ(Cl)]−, which promotes the amorphous to crystalline nature. Consequently, the bulk conductivity of 2D nanosheets exhibits ∼32 mS cm–1, and it is remarkably 102 times higher than 0D nanospheres. Thus, these results promote that the stimuli responsive metallo substituted macrocyclic systems is a significant initiative to manipulate the electronic properties in organic electronics.