Atom-Efficient Halogen–Halogen Interactions Assist One-, Two-, and Three-Dimensional Molecular Zippers

Abstract

Unprecedented multimodal weak interactions are quintessential to create novel supramolecular topologies. Among the plethora of weak interactions, halogen− halogen (X•••X) interactions offer innovative possibilities for the design of multidimensional scaffolds. Herein, we chronicle the state-of-the-art 1D, 2D, and 3D zipper motifs steered by distinct interhalogen interactions, revealing the potential of halogen bonding in engineering biomimetic molecular assemblies. Recurring units of Br 4 synthon, framed by type I and type II atom efficient X•••X interactions in a dibromonaphthathiazole derivative, 2,4-dibromo-5ethoxynaphtho[1,2-d]thiazole (NTB 2 ), forges the molecular zipper. On the basis of the semiclassical Marcus theory of charge transport, the NTB 2 zipper assembly displays selective electron transport along the type II X•••X bonded direction. Band structure analysis classified the crystalline NTB 2 as a wide band gap semiconductor with a band gap of 2.80 eV, respectively. The robustness of the X•••X mediated zipper motif opens up new avenues in the development of advanced functional materials.

Giant Supramolecular Synthons via Cyclic Halogen···Halogen Contacts in Substituted o-Xylenes

“…40 Halogen•••halogen (X 2 ) interactions are utilized for directing noncentrosymmetric crystal packing, 41 to assist in radial chromophoric assembly 42 and supramolecular assembly of luminescence-sensing coordination polymers, 43 and to build fractals, 44 polymeric sheets, 45 bending crystals, 46 blies, 47 donor−acceptor stacks, 48,49 and 3D molecular zippers. 50 Halogens, especially bromine and iodine, can form furcating, hypervalent, and noncovalent interactions with other halogens, 51−53 heteroatoms, 54,55 and metals. 56−58 Furcating noncovalent interactions consist of two-centered (bifurcating) and three-centered (trifurcating) halogen•••halogen contacts, as shown in Scheme 1.…”

“…Halogen bonding has opened up unprecedented possibilities in the design of anion networks, foldamers, polymeric assembly, cylindrical nanostructures, helical assembly, anionic honeycomb networks, ternary cocrystals, and supramolecular nanotubes . Halogen···halogen (X 2 ) interactions are utilized for directing noncentrosymmetric crystal packing, to assist in radial chromophoric assembly and supramolecular assembly of luminescence-sensing coordination polymers, and to build fractals, polymeric sheets, bending crystals, dye assemblies, donor–acceptor stacks, , and 3D molecular zippers …”

“…Our continuous quest to identify new dimensions and archetypes in noncovalent interactions via small organic crystallography ,,− prompted us to systematically examine the crystal structures of a family of bromine-substituted o -xylenes C 8 H 10– n Br n , where n ≤ 4 (Figure ). Here, we report the first evidence of giant Br 8 synthons formed through hypervalent Br···Br contacts in the crystal structure of α,α,α′,α′-tetrabromo- o -xylene 4­(a) .…”

The Effect of Single-Atom Substitution on Structure and Band Gap in Organic Semiconductors

“…Optical band gap tuning in isostructural organic solids with detailed crystallographic studies on the structure–property relations remains elusive. Naphthalene is one of the most extensively used building blocks to construct conjugated materials for blue OLEDs. , Electron-accepting thiazole moieties and naphthalene-based organic materials have been used as semiconductors in organic electronics. , Our continuous efforts in exploring the origin of distinct crystalline supramolecular architectures , of small organic molecules and their potential application as functional materials motivated us to design a series of halogenated naphthathiazoles, illustrating a systematic trend in optical band gap reduction, in the order of increasing atomic number of halogen atoms (Scheme ). We designed novel bipolar naphthalene-based wide-band-gap semiconducting materials fused with an electron-withdrawing thiazole moiety and electron-donating halogen (Cl, Br, I) atom.…”

“…20,21 thalene-based organic materials have been used as semiconductors in organic electronics. 22,23 Our continuous efforts in exploring the origin of distinct crystalline supramolecular architectures 13,24 of small organic molecules and their potential application as functional materials 25 motivated us to design a series of halogenated naphthathiazoles, 26 illustrating a systematic trend in optical band gap reduction, in the order of increasing atomic number of halogen atoms (Scheme 1). We designed novel bipolar naphthalene-based wide-band-gap semiconducting materials fused with an electron-withdrawing thiazole moiety and electron-donating halogen (Cl, Br, I) atom.…”