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Molecules with curved architecture can exhibit unique optoelectronic properties due to the concave‐convex π‐surface. However, synthesizing negatively curved saddle‐shaped aromatic systems has been challenging due to the internal structural strain. Herein, we report the facile synthesis of two polyhexagonal molecular systems, 1 and 2, with saddle shape geometry by judiciously varying the aromatic moiety, avoiding the harsh synthetic methods as that of heptagonal aromatic saddle systems. The unique geometry preferences of B, N, and S furnish suitable curvature to the molecules, featuring saddle shape. The saddle geometry also enables them to interact with fullerene C60, and the supramolecular interactions of fullerene C60 with 1 and 2 modify their optoelectronic properties. Crystal structure analysis reveals that 1, with a small π‐surface, forms a double columnar array of fullerenes in the solid state. In contrast, 2 with a large π‐surface produces a supramolecular capsule entrapping two discrete fullerenes. The intermolecular interactions between B, N, S, and the aryl‐π surface of the host and C60 guest are the stabilizing factors for creating these supramolecular structures. Comprehensive computational, optical, and Raman spectroscopic studies establish the charge transfer interactions between B−N doped heterocycle host and fullerene C60 guest. [ABSTRACT FROM AUTHOR]

Molecules with curved architecture can exhibit unique optoelectronic properties due to the concave‐convex π‐surface. However, synthesizing negatively curved saddle‐shaped aromatic systems has been challenging due to the internal structural strain. Herein, we report the facile synthesis of two polyhexagonal molecular systems, 1 and 2, with saddle shape geometry by judiciously varying the aromatic moiety, avoiding the harsh synthetic methods as that of heptagonal aromatic saddle systems. The unique geometry preferences of B, N, and S furnish suitable curvature to the molecules, featuring saddle shape. The saddle geometry also enables them to interact with fullerene C60, and the supramolecular interactions of fullerene C60 with 1 and 2 modify their optoelectronic properties. Crystal structure analysis reveals that 1, with a small π‐surface, forms a double columnar array of fullerenes in the solid state. In contrast, 2 with a large π‐surface produces a supramolecular capsule entrapping two discrete fullerenes. The intermolecular interactions between B, N, S, and the aryl‐π surface of the host and C60 guest are the stabilizing factors for creating these supramolecular structures. Comprehensive computational, optical, and Raman spectroscopic studies establish the charge transfer interactions between B−N doped heterocycle host and fullerene C60 guest. [ABSTRACT FROM AUTHOR]

Solid‐state luminescence of organic dyes is an elusive frontier, and understanding and designing solid‐state stimuli‐responsive materials is not trivial. "Mechanoluminescence" (ML) or "triboluminescence" (TL), which is associated with fracture or force‐initiated luminescence from a material, is currently attracting new interest. Fracturing the surfaces of organic crystals ordered in noncentrosymmetric space groups can electronically excite the surface and neighboring molecules through piezo‐ or pyroelectric effects, and this can result in luminescence when the molecules relax back to their ground states. The combined duration of these two consecutive phenomena leads to force‐generated luminescence or TL. Although TL has been known for a very long time, examples of TL‐active materials are scarce, but are increasing as synthetic and characterization procedures develop. The question is now whether the relatively rare phenomenon of TL needs to be reevaluated to obtain a broader understanding of the subject. [ABSTRACT FROM AUTHOR]

Synthesis and crystal structures of three porphyrin-based polyfunctional Lewis acids 1- 3 are reported. Intermolecular HgCl ⋅⋅⋅HgCl (linear and μ-type) interactions in the solid state of the peripherally ArHgCl-decorated compound 3 lead to a fascinating 3D supramolecular architecture. Compound 3 shows a selective fluorescence quenching response to picric acid and discriminates other nitroaromatic-based explosives. For the first time, an electron-deficient polyfunctional Lewis acid is shown to be useful for the selective detection and discrimination of nitroaromatic explosives. The Stern-Volmer quenching constant and detection limits of compound 3 for picric acid are the best among the reported small-molecular receptors for nitroaromatic explosives. The electronic structure, Lewis acidity, and selective sensing characteristics of 3 are well corroborated by DFT calculations. [ABSTRACT FROM AUTHOR]

Systematic structural perturbation has been used to fine-tune and understand the luminescence properties of three new 1,8-naphthalimides (NPIs) in solution and aggregates. The NPIs show blue emission in the solution state and their fluorescence quantum yields are dependent upon their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to quench the fluorescence due to the formation of excimers. In contrast, upon aggregation (in THF /H2O mixtures), the NPIs show aggregation-induced emission enhancement (AIEE). The NPIs also show moderately high solid-state emission quantum yields (ca. 10-12.7 %). The AIEE behaviour of the NPIs depends on their molecular rigidity and the nature of their intermolecular interactions. The NPIs 1- 3 show different extents of intermolecular (π-π and CH⋅⋅⋅O) interactions in their solid-state crystal structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that an optimal balance of structural flexibility and intermolecular communication is necessary for achieving AIEE characteristics in these NPIs. [ABSTRACT FROM AUTHOR]

Review: [64 refs. [ABSTRACT FROM AUTHOR]

Thestructure and photophysical properties of two known borylanilines,4-(dimesitylboryl)aniline (1) and 4-(dimesitylboryl)-3,5-dimethylaniline(2), have been investigated. 1and 2have similar donor and acceptor centers but differ in theirmolecular conformations. Compounds 1and 2have been structurally characterized, and they exhibit a rare formof intermolecular N–H- - -π electrostaticinteractions. The structure and photophysical properties of 1and 2are discussed in the context of computationalresults. [ABSTRACT FROM AUTHOR]