1,3,5-Benzene-tri-p-phenylphosphonic Acid. A New Building Block in Supramolecular Chemistry

Abstract

Benzene-1,3,5-tri-p-phenylphosphonic acid, 1,3,5-[p-C 6 H 4 P(O)(OH) 2 ] 3 C 6 H 3 , (8), a novel building block for applications in supramolecular chemistry, was prepared in two steps with an overall yield of 82%. The [Pd(PPh 3 ) 4 ]-catalyzed Arbuzov reaction of 1,3,5-tris(p-bromophenyl)benzene with P(Oi- Pr) 3 afforded benzene-1,3,5-tri-p-phenylphosphonic diisopropyl ester, 1,3,5-[p-C 6 H 4 P(O)(Oi-Pr) 2 ] 3 C 6 H 3 (9). The hydrochloric acid-catalyzed hydrolysis of 9 produced 8, which forms a crystalline salt with p-dimethylaminopyridine (DMAP) in a ratio of 2:3 (as methanol solvate) that was characterized by X-ray crystallography. The supramolecular structure features organic domains of stapled 1,3,5-triphenylbenzene units associated by PO-H • • • OP hydrogen bonds and π-stacking. These staples are horizontally cross-linked by PO-H • • • OP hydrogen bonds. The protonated DMAP molecules fill the voids between the staples and participate in the stabilization of the framework by formation of N-H • • • OP hydrogen bonds. The melting point of the adduct (381 °C) confirms the high thermal stability of the supramolecular framework.

Protein Dimerization on a Phosphonated Calix[6]arene Disc

“…[4a, 8] With amolecular weight of circa 1.1 kDa, p-phosphonatocalix [6]arene [9] (pclx 6 )i salarge,f lexible macrocycle with properties that approximate asmall protein binding site. [8b,d,e] Assuming pK a values of about 2and about 7, [10] the upper-rim phosphonates were singly deprotonated under the experimental conditions ( Figure 1A)a nd the polyanionic pclx 6 is expected to have asignificant charge-charge interaction with polycationic cyt c (net charge + 4a tp H7in 100 mm KCl [11] ). Herein, we demonstrate that pclx 6 induces dimerization and higher-order assemblies of cyt c in buffered solution at low and high salt concentrations.T he pclx 6 -cyt c assemblies were characterized both structurally and thermodynamically by Xray crystallography,s ize exclusion chromatography with Figure 1.…”

“…[4a] Thec alixarene was observed to facilitate protein-protein interactions in the solid state by acting as ah ub for lysine binding.C yt c (12.6 kDa) is an exceptionally well-studied model system, and the interactions of this lysine-rich protein with abroad variety of supramolecular ligands have been characterized. [8b,d,e] Assuming pK a values of about 2and about 7, [10] the upper-rim phosphonates were singly deprotonated under the experimental conditions ( Figure 1A)a nd the polyanionic pclx 6 is expected to have asignificant charge-charge interaction with polycationic cyt c (net charge + 4a tp H7in 100 mm KCl [11] ). [8b,d,e] Assuming pK a values of about 2and about 7, [10] the upper-rim phosphonates were singly deprotonated under the experimental conditions ( Figure 1A)a nd the polyanionic pclx 6 is expected to have asignificant charge-charge interaction with polycationic cyt c (net charge + 4a tp H7in 100 mm KCl [11] ).…”

Organic Proton‐Conducting Molecules as Solid‐State Separator Materials for Fuel Cell Applications

“…Whereas numerous studies have been carried out on the structure and properties of metal phosphonates,51–53 there is sparse information about organic phosphonic acids. In the reported compounds,54–56 the crystal structure is dominated by the formation of strong hydrogen bonds, each phosphonic acid group being potentially a hydrogen bond acceptor and a double hydrogen bond donor at the same time. Therefore, very robust crystalline solids are produced.…”

“…Therefore, very robust crystalline solids are produced. A common feature of phosphonic acid‐containing organic compounds is that they do not form crystals suitable for conventional X‐ray crystallography and only single‐crystalline salts with p ‐dimethylaminopyridine (DMAP) can be obtained 54, 57, 58…”

Effect of electron donating substituents on supramolecular structure of salts having phenylphosphonic acid and pyrazoles

“…The use of phosphonic acid in the construction of 2D or 3D hydrogen bonded supramolecular material and crystal engineering is less developed in comparison to carboxylic acid [12][13][14] and has been limited mainly to metal phosphonates, organic-inorganic hybrid materials, co-crystals and organic salts. Different phosphonic acids have been utilized for the construction of organic salts and co-crystals with a number of organic bases and neutral molecules especially with aniline, ethylenediamine, p-phenylazoaniline, hexamethylenediamine, 2,2 0 -bipyridine, 4,4 0 trimethylene-dipyridine, hexamacrocyclic crown ethers, 4,4 0 -bipyridine, p-dimethylaminopyridine and guanidinium chloride [11,[15][16][17][18][19][20]. In addition, they are widely used for the preparation of metal complexes too [21][22][23][24][25][26][27][28][29][30].…”