Benzene-1,4-diboronic acid–4,4′-bipyridine–water (1/2/2)

Vega, Araceli; Zarate, Maria; Tlahuext, Hugo; Höpfl, Herbert

doi:10.1107/s0108270110009121

Cited by 6 publications

(8 citation statements)

References 18 publications

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“…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].…”

Section: Introductionmentioning

confidence: 93%

“…PhenylScheme 2 Various conformations possible for the -B(OH) 2 functionality. boronic acids have been shown to form OH···N hydrogen bonds with several pyridine based linear spacer ligands [25,27]. The possible non-covalent interactions with N-donor compounds together with the conformational flexibility render this functionality an interesting one in the tool kit of the crystal engineer.…”

Section: Introductionmentioning

confidence: 99%

“…Although the fragment prefers the syn,anti conformation in the native state, a large variety of interaction motifs are present in the molecular complexes because of conformational flexibility. The complexity in utilizing phenylboronic acids in design and synthesis of molecular adducts is evident from the six types of hydrogen bonding motifs experimentally observed in the adducts of boric/boronic acids with 4,4'-bipyridine [27].…”

Section: Introductionmentioning

confidence: 99%

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

2011

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Phenylboronic acids can exist, in principle, in three different conformers (syn,syn; syn,anti and anti,anti) with distinct energy profiles. In their native state, these compounds prefer the energetically favored syn,anti-conformation. In molecular complexes, however, the functionality exhibits conformational diversity. In this paper we report a series of co-crystals, with N-donor compounds, prepared by a design strategy involving the synthons based on the syn,syn-conformation of the boronic acid functionality. For this purpose, we employed compounds with the 1,2-diazo fragment (alprazolam, 1H-tetrazole, acetazolamide and benzotriazole), 1,10-phenanthroline and 2,2'-bipyridine for the co-crystallization experiments. However, our study shows that the mere presence of the 1,2-diazo fragment in the coformer does not guarantee the successful formation of co-crystals with a syn,syn-conformation of the boronic acid.Typical cyclic OH···N hydrogen bonds formed by boronic acids with alprazolam (a) and 1,10-phenanthroline (b).The -B(OH) 2 fragment makes unsymmetrical O-H···N heterosynthons with alprazolam (ALP) and 1,10-phenanthroline (PHEN). In the co-crystals of phenylboronic acids with 1H-tetrazole (TETR) and 2,2'-bipyridine (BPY), the symmetrical boronic acid dimer is the major synthon. In the BPY complex, boronic acid forms linear chains and the pyridine compound interacts with the lateral OH of boronic acid dimers that acts as a connector, thus forming a ladder structure. In the TETR complex, each heterocycle interacts with three boronic acids. While two boronic acids interact using the phenolic group, the third molecule generates O-H···N hydrogen bonds using the extra OH group, of -B(OH) 2 fragment, left after the dimer formation. Thus, although molecules were selected retrosynthetically with the 1,2-diazo fragment or with nearby hetero-atoms to induce co-crystal formation using the syn,syn-orientation of the -B(OH) 2 functionality, co-crystal formation is in fact selective and is probably driven by energy factors. Acetazolamide (ACET) contains self-complementary functional groups and hence creates stable homosynthons. Phenylboronic acids being weak competitors fail to perturb the homosynthons and hence the components crystallize separately. Therefore, besides the availability of possible hydrogen bond acceptors in the required position and orientation, the ability of the phenyl-boronic acid to perturb the existing interactions is also a prerequisite to form co-crystals. This is illustrated in the 1910 Varughese S, et al. Sci China Chem December (2011) Vol.54 No.12 table below. In the case of ALP, PHEN and BPY, the native structures are stabilized by weak interactions and may be influenced by the boronic acid fragment. Thus phenylboronic acids can attain co-crystals with those compounds, wherein the cyclic O-H···N hydrogen bonds are stronger than the individual homo-interactions. This can lower the lattice energy of the molecular complex as compared with the individual crystals.Heterosynthons formed by boronic a...

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2011

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“…The strong hydrogen bond donor ability and relatively weak hydrogen bond acceptance of boric acid and its derivatives makes them excellent candidates for crystal engineering and co-crystal formation. [1][2][3][4] Simple aryl boronic acids tend to form cyclic hydrogen-bonded dimers in the solid state and this motif results in additional hydrogen atoms capable of interacting with guest species. A search of the 2017 version of the Cambridge Structural Database (CSD 5 ) reveals some 14 neutral organic co-crystal structure determinations incorporating boric acid itself.…”

Section: Introductionmentioning

confidence: 99%

“…A search of the 2017 version of the Cambridge Structural Database (CSD 5 ) reveals some 14 neutral organic co-crystal structure determinations incorporating boric acid itself. Boric acid co-crystals are typically formed with nitrogen bases such as pyridines or imidazoles, 3,6,7 or highly polar oxygen acceptors such as triphenylphosphine oxide. 8 There are also a number of fascinatingly complex inorganic and ionic boric acid co-crystals such as tetraethylammonium carbonate urea clathrate bis(boric acid) monohydrate.…”

Section: Introductionmentioning

confidence: 99%

Boric acid co-crystals in guar gelation

et al. 2017

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Crystal Engineering of Multiple Supramolecular Heterosynthons in Cocrystals of Boronic Acids: Structures, Photoreactivities, and Catalysis

Barba Hernández,

Vasquez-Ríos,

Höpfl

et al. 2024

Crystal Growth & Design

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Cocrystallizations of four para-substituted arylboronic acids, namely, 4-carboxyphenylboronic acid (4-cpba), 4aminophenylboronic acid (4-apba), 4-aminocarbonylphenylboronic acid (4-acpba), and 4-nitrophenylboronic acid (4-npba), with trans-1,2-bis(4-pyridyl)ethylene (bpe) afforded seven multicomponent crystals, i.e., [(4-cpba) 2 (bpe) 3 ], [(4-apba) 2 (bpe) 3 ], [(4acpba) 2 (bpe)], [(4-apba)(bpe) 2 (H 2 O) 2 ], [(4-acpba)(bpe) 2 (H 2 O) 2 ], [(4-cpbhme)(bpe)], and [(4-npbhme) 2 (bpe)], with the last two containing the hemimethyl ester (hme) of 4-cpba and 4-npba, respectively. SCXRD analyses reveal (B)O−H•••N pyr hydrogen bonds among the boronic acid (or hme) and bpe molecules. With the presence of an additional hydrogen-bonding site in the paraposition of the boronic acids, the formation of 1D strands is induced, which generally supports interstrand π-interactions to yield 2D layer structures. In most cases, adjacent bpe molecules in the crystal structures fulfill the topological criteria for a [2 + 2] photodimerization reaction and react to yield rctt-tetrakis(4-pyridyl)cyclobutane (tpcb). UV photoreaction experiments on single crystals for [(4-cpba) 2 (bpe) 3 ] resulted in a single-crystal-to-single-crystal (SCSC) transformation. The boronic acid 4-cpba was also used to direct the photoreaction catalytically.

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Benzene-1,4-diboronic acid–4,4′-bipyridine–water (1/2/2)

Cited by 6 publications

References 18 publications

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

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

Boric acid co-crystals in guar gelation

Crystal Engineering of Multiple Supramolecular Heterosynthons in Cocrystals of Boronic Acids: Structures, Photoreactivities, and Catalysis

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