Halogen bonded supramolecular complexes and networks

Hydrogen-Bonding Motifs in Piperazinediium Salts

“…The only tentative interaction appears to be a close contact between the chlorine atoms of nearby anions with a Cl· · · Cl distance of ca. 3.3 Å which is within the sum of the van der Vaals radii, and a C-Cl· · · Cl angle of 151° [29][30][31]. These geometric parameters are in excellent agreement with those set out by Awwadi et al [32,33] based on database and computational studies, for halogen bonding between sp 3 hybridized carbon-halogen groups and are classified as -type I‖ halogen· · · halogen interactions.…”

Halogen bonding at the ATP binding site of protein kinases: Preferred geometry and topology of ligand binding

“…Specific interactions between the halogen atoms (Cl, Br, I) of halogenated ligands and the electron pairs of oxygen/nitrogen/sulfur have been identified in many crystal structures of supramolecular ensembles [1][2][3] as well as in complexes between biomolecules and halogenated ligands [4][5][6][7][8]. In both cases this is based in part on the observation that the distance between a halogen atom and its electron-donating partner is significantly lower than the sum of their vdW radii ( Figure 1).…”

“…The apparently largest values for X-bond contributions in solution were estimated, with the aid of IR spectroscopy, for CF 3 -X…N(CH 3 ) 3 in liquid noble gases, as 2.1, 4.4 and 6.8 kcal/mol for X-bonds involving Cl, Br and I, respectively [13]. However, the fundamental problem concerning the relation between hydrophobic and electrostatic interactions, and the enthalpy of hydrogen vs. halogen bond formation, remains to be resolved.…”

Role of Weak Hydrogen Bonds and Halogen Bonds in 5-Halo-1,3-dimethyluracils and Their Cocrystals—A Combined Experimental and Computational Study

“…6 Despite the work already performed, there remains a need to investigate small biomolecular systems where XBs and non-conventional HBs, such as C-H … O, are simultaneously present, as the latter interactions are ubiquitous in many small molecule crystal structures 24,25 and advantageously used for enhancing the efficiency of weak base pairing in DNA. [26][27][28][29][30][31][32][33] Due to our continuing interest in the potential of pyrimidine nucleobases for crystal engineering strategies underpinned by multiple HBs [34][35][36][37][38][39][40][41][42][43][44][45] and our involvement in studies of systems exhibiting halogen bonding via alternative donors (halogen atom not polarized by fluorine) and acceptors (such as anions), [46][47][48][49][50][51][52][53][54][55][56][57][58][59] we were interested in search for systems that could be used to investigate the role of concurrent XBs and non-conventional HBs in the control of sequence, structure and flexibility of DNA halogenated within the natural tract. For this purpose, 5-halogenated derivatives (DMXU; X=F, Cl, Br, I) of N,N-1,3-dimethyluracil (DMHU) and their mixed cocrystals are ideal candidates because of several advantageous properties.…”