A fluorinated distyrylanthracene (DSA) derivative, 9, 10-bis((E)-4-(trifluoromethyl)styryl)anthracene abbreviated as 4FDSA with two crystalline polymorphs (4FDSA-G (green emission) and 4FDSA-O (orange emission)), showing remarkable aggregation-induced enhanced emission and mechanofluorochromic characteristics, was developed. One of the polymorphs in its crystalline arrangement exhibits the hardly seen F…F interactions. It questions the conventional belief of the non-polarisable nature of fluorine atoms in forming the halogen bond. The twisted molecular conformation facilitated by the various supramolecular interactions resulted in the formation of another intensely emissive bluer nanocrystal (4FDSA-NC) at aggregating conditions. Even though, the both polymorphs show distinct tricolor luminescence switching on the action of mechanical force, fumigation of ground crystals with solvent vapor resulted in the formation of a more thermodynamically favorable 4FDSA-NC form. The work demonstrates the effect of supramolecular interactions assisted conformational changes in tuning the unique mechanofluorochromic characteristics of the polymorphic crystals.
In the title compound, C21H17BrN2O4S2, the indole ring system subtends dihedral angles of 85.96 (13) and 9.62 (16)° with the planes of the N- and C-bonded benzene rings, respectively. The dihedral angles between the benzene rings is 88.05 (17)°. The molecular conformation is stabilized by intramolecular N—H⋯O and C—H⋯O hydrogen bonds and an aromatic π–π stacking [centroid-to-centroid distance = 3.503 (2) Å] interaction. In the crystal, short Br⋯O [2.9888 (18) Å] contacts link the molecules into [010] chains. The chains are cross-linked by weak C—H⋯π interactions, forming a three-dimensional network.
In the title compound, C24H21NO3S, the dihedral angles between the indole ring system (r.m.s. deviation = 0.030 Å) and the sulfur and ethylene-bonded benzene rings are 80.2 (2) and 49.29 (15)°, respectively. The dihedral angle between the pendant benzene rings is 37.7 (2)°. In the crystal, molecules are linked by C—H⋯O hydrogen bonds and weak C—H⋯π and π–π [centroid-to-centroid distances = 3.549 (2) and 3.743 (3) Å] interactions, forming a three-dimensional network.
In the title compound, C27H21NO4S, the dihedral angles between the carbazole ring system (r.m.s. deviation = 0.015 Å) and the sulfur-bonded and directly linked benzene rings are 79.98 (11) and 53.51 (18)°, respectively. The benzene rings subtend a dihedral angle of 48.4 (2)°. The ethyl side chain of the ester group has an extended conformation [C—O—C—C = −172.3 (3)°]. In the crystal, inversion dimers linked by pairs of weak C—H⋯O hydrogen bonds generate R
2
2(22) loops. The dimers are linked by weak C—H⋯π and π–π [centroid-to-centroid distances ranging from 3.5042 (14) to 3.888 (2) Å] interactions, thereby forming a three-dimensional supramolecular network.
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