Structurally diverse macrocycle co-crystals for solid-state luminescence modulation.

Li, Bin; Liu, Lingling; Wang, Yuan; Liu, Kun; Zheng, Zhe; Sun, Shougang; Hu, Yongxu; Li, Liqiang et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Organic co-crystals offer an opportunity to fabricate organic functional materials. Traditional co-crystals are generally packed following the segregated or mixed stacking mode, leading to the lack of structural and functional diversity. Herein, we report three sets of macrocycle co-crystals with identical co-constitutions. The macrocycle co-crystals differ in the stoichiometric ratios (2:1, 1:1, and 2:3) of the constituents and molecular packing modes. The co-crystals are constructed using triangular pyrene-macrocycle and 1,2,4,5-tetracyanobenzene exploiting exo-wall charge-transfer interactions. Interestingly, the three co-crystals exhibit distinct, tunable emission properties. The corresponding emission peaks appear at 575, 602, and 635 nm, covering yellow via orange to red. The X-ray diffraction analyses and the density functional theory calculations reveal the superstructure-property relationships that is attributed to the formation of different ratios of charge-transfer transition states between the donor and acceptor motifs, resulting in red-shifted luminescence.