Di(4-fluorobenzenesulfonyl)amine (DFBSA), di(4-chlorobenzenesulfonyl)amine (DCBSA) or di(4-bromobenzenesulfonyl)amine (DBBSA) were co-crystallized with equimolar amounts of pyridine-N-oxide (PyO), dimethyl formamide (DMF) or 1,3-dimethylurea (DMU), respectively, to form the supramolecular complexes DFBSA·PyO (1; triclinic, space group P1 , Z = 1), DCBSA·DMF (2; monoclinic, P21/n, Z = 1) and DBBSA·DMU (3; triclinic, P1 , Z = 1). Throughout the triad, the molecules are ordered into lamellar layers parallel to the xy plane. Owing to the folded conformations of the disulfonylamines, the layers display an inner polar region of oxygen bases and (SO2)2NH groups, outer apolar regions of aromatic rings, and interlayer regions hosting the halogen atoms. These arrays mimic the formerly reported structures of a series of ionic metal di(arenesulfonyl)amides. The intralamellar connectivity is governed by conventional hydrogen bonding and weak C-H···O bonds, the former comprising in structure 1 a very strong N-H···O-N interaction [N···O 250,9(2) pm, N-H···O 171(3)°], in 2 an N-H···O=C bond, and in 3 a set of one S2N-H···O=C and two N-H(urea)···O=S bonds. A centrosymmetric (PyO)2 dimer is present in structure 1. The juxtapositions of adjacent layers reflect halogen-specific recognition patterns (1: three short C-H···F sequences, all F···F distances beyond the van der Waals limit dW; 2: one short C-H···Cl sequence and one close Cl ··· Cl contact < dW, all other Cl ··· Cl > dW; 3: four short C-H···Br sequences and one close Br···Br contact < dW, all other Br···Br > dW). The interhalogen contacts in 2 and 3 are of the type I, as characterized by θ(C-X···X')≈ θ(C'-X' ··· X); the four angles θ lie in the range 166-175°
Carbohydrate – Protein aromatic ring interactions beyond CH/π interactions: A Protein Data Bank survey and quantum chemical calculations
