On the Organizing Role of Water Molecules in the Assembly of Boronic Acids and 4,4′-Bipyridine: 1D, 2D and 3D Hydrogen-Bonded Architectures Containing Cyclophane-Type Motifs

Abstract

4,4′-Bipyridine has been combined with boric acid and four different boronic acids (1,3- and 1,4-benzenediboronic acid, 3-aminophenylboronic acid, 4-acetylphenylboronic acid) to give 1:1 (with boric acid) and 1:2 adducts (with arylboronic acids), which have been characterized by X-ray diffraction analysis. The supramolecular solid-state structures are composed of hydrogen-bonded networks with (B)O−H···N, (B)O−H···O, C−H···O, C−H···N, C−H···π, π···π and C−H···B interactions. The comparative analysis of the boric/boronic acid−4,4′-bipyridine adducts has revealed that water molecules play an important role as spacer molecules in RB(OH)2···py synthons, since their incorporation in the hydrogen-bonding patterns allows optimization of π−π interactions. The structural relationship between the dihydroxyboryl and the carboxyl group has been analyzed, showing that the former can form at least three different hydrogen-bonding patterns with pyridines. This can be attributed to the presence of two acidic hydrogen atoms instead of one (B(OH)2 ↔ C(O)OH). The three motifs have been examined also by ab initio calculations, confirming that for the three cases the (B)O−H···N interaction energies are similar.

Exploration of the Luminescence Properties of Organic Phosphate Salts of 3‐Quinoline‐ and 5‐Isoquinolineboronic Acid

“…In 5IQBA‐1NP similar π‐bonded dimers with antiparallel oriented isoquinolinium substituents are present, but the π ··· π contacts are now concentrated at the π–electron cloud of the atom chain C1–C4 with Cg1 ··· Cg1 (Cg1 = N1, C1–C3, C8, C9) distances (4.733 Å) that are significantly larger than in 3QBA‐1NP (Figure e). There are three B ··· N/C π contacts with the pyridinium moiety of the B‐isoquinolinium substituent, for which the central B ··· C distance of 3.161 Å is significantly shorter than the remaining contacts (3.327 and 3.632 Å) (Table ) , . Despite these differences, the supramolecular organizations of 3QBA‐1NP and 5IQBA‐1NP are quite similar within the (001) planes, as seen from a comparison of Figure d and Figure d.…”

Bis‐Imine Boronic Esters Obtained by One‐Step Multicomponent Reactions. Synthesis and X‐Ray Diffraction Structural Analysis

“…Interesting, each B(OH) 2 moiety is connected to five neighboring molecules of 1 b trough hydrogen bonding interactions, two O−H⋅⋅⋅N contacts and three C−H⋅⋅⋅O contacts (Figures 5,). The hydrogen bonds and packing effects influence the less common cis behind orientation for the hydrogen atoms in the fragment B(OH) 2 , in most cases these hydrogens are oriented cis in front or in a trans disposition . The above secondary interactions supported the 2D polymeric frameworks in which the diboronic acids molecules connects the imine boronic esters chains (Figure ).…”

Phenylboronic acids in crystal engineering: Utility of the energetically unfavorable syn,syn-conformation in co-crystal design

“…Molecules used for co-crystallization studies Although the syn,syn-conformer is found in the boronic acid-carboxylate synthon [28], the existence of this conformer with N-heterocycles is relatively rare and usually happens as a chance or with the assistance from lattice water [25,27,29]. The present study is an extension of our earlier work on the synthon preferences of various functional groups towards a 1,2,4-triazole containing drug-alprazolam (ALP) [30].…”