Arylphosphonic Acids Research Articles

Pentafluorophenylphosphonic Acid as a New Building Block for Molecular Crystal Fabrication

Molecular crystals have been prepared from pentafluorophenylphosphonic acid (4). These include 2C6F5PO3H2·H2O (4·4·H2O), [(C6F5PO3H–)(H3O+)]·C6F5PO3H2 (4·4–·H3O+), [(C6F5PO3H–)(NH4+)]·C6F5PO3H2 (4·4–·NH4+), [(C6F5PO3H–)(Me2NH2+)] (4–·DMA+), [(C6F5PO3H–)(Me2NH2+)]·H2O (4–·DMA+·H2O), [(C6F5PO3H–)(Me2NH2+)]·C6F5PO3H2 (4·4–·DMA+), [(C6F5PO3H–)(Me2NH2+)0.5(NH4+)0.5] (4–·DMA+·NH4+), and [(C6F5PO3H–)(+H3NCH2CO2H)] (4–·Gly+), where DMA+ = dimethylammonium and Gly+ = glycinium. All of the assemblies incorporate an ammonium cation, a water molecule, or a hydronium ion in their structure, and these included species act as adhesive agents. They interact via O/N–H···O hydrogen bonds and C–H···O contacts with PO3H2 or PO3H– moieties located in polar sheets, forcing the building blocks to assemble with a 2D layered arrangement. The robustness of this arrangement is reminiscent of that observed in metal arylphosphonates and guanidinium sulfonates, yet the architectures described herein differ significantly from the second family of compounds in two aspects: the lack of puckering of the layers and the absence of void spaces to accommodate solvent molecules. Interestingly, however, just as in guanidinium sulfonates, two structural types have been recognized depending on the size of the included species: a single-layer stacking motif and a bilayer stacking motif. Even though hydrogen bonding is the prevailing interaction in these systems, the use of perfluoroaryl groups is also central, as these moieties bring about weak C–F···π, π···π, C–F···F–C, C–F···H–C, and O/N–H···F–C interactions that help to increase the cohesion of the nonpolar regions. As a result, new architectures are created that significantly differ in some cases from those prepared from phenylphosphonic acid. However, the weakness of perfluoroaryl-based interactions is also their strength, as these interactions are sufficiently flexible to allow changes in the organization of the aromatic groups in response to changes (ionization) occurring in the polar regions, as observed in the structures of 4·4·H2O and 4·4–·H3O+. This situation is quite unusual and may be regarded as some kind of acidity-modulated polymorphism. The work presented here broadens the knowledge on molecular crystal formation with arylphosphonic acids, a research area largely dominated by carboxylic and sulfonic acids. Also, the computational evaluation of 4·4·H2O and 4·4–·H3O+ described in this report suggests that this family of fluorinated compounds may show interesting prospects as molecular semiconductors, a research area that is currently receiving increased attention.

Fluorescent Arylphosphonic Acids: Synergic Interactions between Bone and the Fluorescent Core.

Herein, we report the third generation of fluorescent probes (arylphosphonic acids) to target calcifications, particularly hydroxyapatite (HAP). In this study, we use highly conjugated porphyrin‐based arylphosphonic acids and their diesters, namely 5,10,15,20‐tetrakis[m‐(diethoxyphosphoryl)phenyl]porphyrin (m ‐H8TPPA‐OEt8) and 5,10,15,20‐tetrakis [m‐phenylphosphonic acid]porphyrin (m ‐H8TPPA), in comparison with their positional isomers 5,10,15,20‐tetrakis[p‐(diisopropoxyphosphoryl)phenyl]porphyrin (p ‐H8TPPA‐iPr8) and 5,10,15,20‐tetrakis [p‐phenylphosphonic acid]porphyrin (p ‐H8TPPA), which have phosphonic acid units bonded to sp2 carbon atoms of the fluorescent core. The conjugation of the fluorescent core is thus extended to the (HAP) through sp2‐bonded −PO3H2 units, which generates increased fluorescence upon HAP binding. The resulting fluorescent probes are highly sensitive towards the HAP in rat bone sections. The designed probes are readily taken up by cells. Due to the lower reported toxicity of (p ‐H8TPPA), these probes could find applications in monitoring bone resorption or adsorption, or imaging vascular or soft tissue calcifications for breast cancer diagnosis etc.

Synthesis, characterization and properties of titanium phosphonate clusters

Titanium phosphonate clusters were synthesized by the reactions of titanium tetraisopropoxide (Ti(OiPr)4) with arylphosphonic acids (ArPO3H2, Ar = Ph, 1-Nap, 4-MeOPh, 4-FPh, 4-ClPh, 4-BrPh, and 4-BrBn) and H2O in tetrahydrofuran (THF) at room temperature. [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PAr)3]·solv (Ar = Ph (1), 1-Nap (2), 4-MeOPh (3), 4-FPh (4), 4-ClPh (5); solv = thf for 1 and 2 or 2-propanol for 3–5) were isolated as new Ti4P3-type clusters, while Ti7(μ3-O)2(OiPr)6(μ-OiPr)6(O3PBnBr)6 (6) was isolated as a Ti7P6-type cluster. A co-crystal of Ti4P3- (7a) and Ti7P6-type (7b) clusters were obtained when 4-BrPhPO3H2 was used, and [Ti(OiPr)(acac)(O3PPh)]4 (8), a new cage cluster, was obtained when Ti(acac)2(OiPr)2 (Hacac = acetylacetone) was reacted with PhPO3H2.

ChemInform Abstract: A Robust and Simple Protocol for the Synthesis of Arylfluorophosphonates.

AbstractA sequence is developed for the conversion of arylphosphonic acids into arylfluorophosphonates through selective monoesterification and subsequent fluorination.

ChemInform Abstract: Phosphaannulation of Aryl‐ and Benzylphosphonic Acids with Unactivated Alkenes via Palladium‐Catalyzed C—H Activation/Oxidative Cyclization Reaction.

An efficient phosphaannulation via palladium(II)-catalyzed CH activation/oxidative cyclization by the 6-endo mode is reported for the synthesis of 3-substituted phosphaisocoumarins from the reaction of arylphosphonic acids with unactivated alkenes under aerobic conditions. Also, α,α-disubstituted benzylphosphonic acids were phosphaannulated with unactivated alkenes, producing phosphaisochromanones having (Z)-alkylidenyl groups via anti-phosphoryloxypalladation by the 6-exo mode.

Phosphaannulation of Aryl‐ and Benzylphosphonic Acids with Unactivated Alkenes via Palladium‐Catalyzed CH Activation/Oxidative Cyclization Reaction

AbstractAn efficient phosphaannulation via palladium(II)‐catalyzed CH activation/oxidative cyclization by the 6‐endo mode is reported for the synthesis of 3‐substituted phosphaisocoumarins from the reaction of arylphosphonic acids with unactivated alkenes under aerobic conditions. Also, α,α‐disubstituted benzylphosphonic acids were phosphaannulated with unactivated alkenes, producing phosphaisochromanones having (Z)‐alkylidenyl groups via anti‐phosphoryloxypalladation by the 6‐exo mode.magnified image

Synthesis of Borophosphonate Cage Compounds: Influence of Substituent and Concentration Effects on Product Distribution in Condensation Reactions of Aryl Phosphonic Acids and Boronic Acids

Aryl borophosphonate cage compounds [ArPO3BAr′]n with n = 4 or 6 were synthesized by condensation reactions of ArP(O)(OH)2 and Ar′B(OH)2. (3,5-tBu2-Ph)P(O)(OH)2 (1) reacts with arylboronic acids that contain electron-withdrawing substituents to form borophosphonate tetramers [Ar1PO3BAr2]4 (Ar1 = 3,5-tBu2-Ph; Ar2 = o-Br-Ph, o-CF3-Ph, p-CF3-Ph, p-CHO-Ph; 3a–d) and hexamers [Ar1PO3BAr2]6 (Ar2 = p-CF3-Ph, p-CHO-Ph; 4c–d) in 80–93% NMR yield. For Ar2 = p-CF3-Ph and p-CHO-Ph, both products were observed, with the tetramer being favored under dilute reaction conditions and the hexamer favored under concentrated reaction conditions. Interconversion between tetramer (3c or 3d) and hexamer (4c or 4d) was observed at room temperature and above in toluene. The phosphine phosphonic acid (2-PPh2-Ph)P(O)(OH)2 (6) reacts with arylboronic acids that contain electron-withdrawing substituents to form tetramers [Ar1PO3BAr2]4 (Ar1 = 2-PPh2-Ph; Ar2 = p-CF3-Ph, p-CHO-Ph; 7c–d) in 70–75% NMR yield. The reactions of 1 or 6 with (p-tolyl)B(OH)2 (2f), and the reaction of 6 with (o-CF3-Ph)B(OH)2 (2b), yield only trace amounts of borophosphonate cage compounds and instead afford the corresponding [ArBO]3 boroxines and condensation products with unknown structures.

Synthesis and Proton Dissociation Properties of Arylphosphonates: A Microwave‐Assisted Catalytic Arbuzov Reaction with Aryl Bromides

ABSTRACTA series of substituted diethyl arylphosphonates was synthesized by the microwave‐assisted Arbuzov reaction of triethyl phosphite and aryl bromides in the presence of NiCl2 as the catalyst under solvent‐free conditions in good yields. The resulting phosphonates were hydrolyzed to the corresponding arylphosphonic acids whose acidity was evaluated by physicochemical methods.

Ag(i)-mediated formation of pyrophosphonate coupled with C–C bond cleavage of acetonitrile

A general approach to obtain pyrophosphonates is achieved by reacting arylphosphonic acids with AgNO(3) in CH(3)CN under solvothermal conditions; the process is coupled with the C-C bond cleavage of acetonitrile and the formation of novel complexes [Ag(n)(RPO(2)(O)O(2)PR)(m)](CN); the mechanism of the process is proposed.

Phosphonic Acid Modification of Indium−Tin Oxide Electrodes: Combined XPS/UPS/Contact Angle Studies

Indium−tin oxide (ITO) electrodes have been modified with both fluorinated alkyl and aryl phosphonic acids [n-hexylphosphonic acid (HPA) and n-octadecylphosphonic acid (ODPA); 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl phosphonic acid (FHOPA), pentafluorobenzyl phosphonic acid (PFBPA), and tetrafluorobenzyl-1,4-diphosphonic acid (TFBdiPA)]. These are modifiers designed to control both wetting properties toward nonpolar molecular solids and to provide a wide range of tunability in effective surface work function. The molecular nature of surface attachment and changes in electronic and wetting properties were characterized by X-ray photoelectron spectroscopy (XPS), UV-photoelectron spectroscopy (UPS), photoelastic modulation infrared reflection−absorption spectroscopy (PM-IRRAS), and contact angle measurements using both water and hexadecane. Interface dipoles from the PA modifiers contribute to shifts in the low kinetic energy regions of UPS spectra (local vacuum level shifts, which translate into change...

Synthesis of Alkyl‐ and Arylphosphonic Acid Monoesters by Direct Esterification of Dibasic Phosphonic Acids in the Presence of an Arsonic Acid Catalyst.

Partial hydrolysis of a diester, hydrolysis of the monochloro monoester, or alcoholysis of a phosphonic acid anhydride generally is used to prepare monoesters of alkyl- and arylphosphonic acids. Limited cases have been reported for the esterification of a dibasic phosphonic acid to yield the monoester, and none of these methods are as simple as the analogous method for preparing carboxylic acid esters, in which the carboxylic acid is esterified with an alcohol in the presence of an acid catalyst. Described is a method for preparing monoesters of alkyl- and arylphosphonic acids by direct esterification with an alcohol in the presence of a catalytic amount of phenylarsonic acid. The water formed during the reaction is removed azeotropically. For example, methylphosphonic acid was esterified in good yield to give its isopropyl, butyl, cyclohexyl, bornyl, and octadecyl monoesters. Similarly prepared are the ethyl, butyl, hexyl, and 2-(ethylthio)ethyl monoesters of phenylphosphonic acid, as well as 2-isopropox...

SYNTHESIS OF ALKYL- AND ARYLPHOSPHONIC ACID MONOESTERS BY DIRECT ESTERIFICATION OF DIBASIC PHOSPHONIC ACIDS IN THE PRESENCE OF AN ARSONIC ACID CATALYST

Partial hydrolysis of a diester, hydrolysis of the monochloro monoester, or alcoholysis of a phosphonic acid anhydride generally is used to prepare monoesters of alkyl- and arylphosphonic acids. Limited cases have been reported for the esterification of a dibasic phosphonic acid to yield the monoester, and none of these methods are as simple as the analogous method for preparing carboxylic acid esters, in which the carboxylic acid is esterified with an alcohol in the presence of an acid catalyst. Described is a method for preparing monoesters of alkyl- and arylphosphonic acids by direct esterification with an alcohol in the presence of a catalytic amount of phenylarsonic acid. The water formed during the reaction is removed azeotropically. For example, methylphosphonic acid was esterified in good yield to give its isopropyl, butyl, cyclohexyl, bornyl, and octadecyl monoesters. Similarly prepared are the ethyl, butyl, hexyl, and 2-(ethylthio)ethyl monoesters of phenylphosphonic acid, as well as 2-isopropoxyethyl hydrogen ethylphosphonate and 2-methoxyethyl hydrogen benzylphosphonate.

Oxidative Heck‐Type Reaction Involving Cleavage of a Carbon—Phosphorus Bond of Arylphosphonic Acids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Oxidative Heck-Type Reaction Involving Cleavage of a Carbon−Phosphorus Bond of Arylphosphonic Acids

Cleavage of a carbon-phosphorus bond is achieved under palladium catalysis in an oxidative Heck-type reaction which exploits arylphosphonic acids. The reaction of arylphosphonic acids with alkenes provides arylation products in good yields in the presence of TBAF with trimethylamine oxide as an oxidant.

Syntheses, Spectroscopy, Structures, and Reactivity of Neutral Cubic Group 13 Molecular Phosphonates

The syntheses of cubic group 13 molecular phosphonate cages of the formulas [RPO3MR‘]4 (R = Me, Et, t-Bu, Ph; MR‘ = BEt, BBu-s, GaMe, InMe; all combinations, 1−16), [t-BuPO3AlBu-i]4 (17), and [MePO3AlBu-t]4 (18) have been achieved by the facile reactions of alkyl- or arylphosphonic acids with the corresponding alkyl compounds under appropriately chosen reaction conditions. Compounds 1−18 have been characterized by analytical and spectroscopic techniques. In all cases, the central M4O12P4 inorganic cubic framework is shielded by alkyl/aryl groups. The phosphonates bearing tert-butyl groups on the phosphorus are highly soluble in common organic solvents such as n-hexane, Et2O, and THF. The molecular structure of representative examples [t-BuPO3BEt]4 (3) and [t-BuPO3BBu-s]4 (7) as determined by single-crystal X-ray diffraction studies reveal the presence of a central cubic M4O12P4 framework that is analogous to those found in alumino- and gallophosphate materials. Most of these cubic phosphonates are air and moisture stable. In the presence of excess phenol, it is possible to react one of the M−C bonds at the corners of the cube 3 and prepare its monophenoxy derivative [t-BuPO3BEt]3[t-BuPO3B(OPh)] (19) in very low yields. However, in spite the presence of reactive M−C bonds, these cubic phosphonates are unreactive toward alcohols, amines, carboxylic acids, H2O, and air under ambient conditions.

Synthesis of 2-Mercapto- and 2-Hydroxy-Substituted Diphenylphosphines for use as Dianionic Bidentate Ligands and Polydentate Ligand Precursors

Abstract As part of our studies into the synthesis of polydentate phosphine-containing ligands, we have investigated the preparation of the phosphines (4; X[dbnd]O) and (4; X[dbnd]S). These are of interest both as potential dianionic bidentate ligands and as useful precursors of more complex polydentate ligand systems. A synthesis of the thiol system (4; X[dbnd]S) from 1,2-dinitrobenzene has been previously reported [1], but the observation [2], that 2-bromoaryl esters of phosphoric acid rearrange to give esters of arylphosphonic acids in the presence of alkyl lithiums, led us to consider whether a similar type of rearrangement might provide a convenient approach to both (4; X[dbnd]S) and (4; X[dbnd]O).

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS 94. SYNTHESES OF 1-HYDRAZINO- AND 2-HYDRAZINO-ALKYLPHOSPHONIC ACIDS AND DERIVATIVES THEREOF

Abstract A series of 1-hydrazino- and 2-hydrazino-alkyl (aryl) phosphonic acids and their derivatives were prepared from the corresponding hydrazono compounds by treatment with sodium cyanoborohydride or with the borane-tetrahydrofuran complex, respectively.

ChemInform Abstract: A Novel Asymmetric Synthesis of α‐ and β‐Amino Aryl Phosphonic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Studies on Organophosphorus Compounds. Part 75. A Facile Synthesis of 1‐(Hydroxyamino)alkyl(or aryl)phosphonic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Studies on Organophosphorus Compounds; LXXV: A Facile Synthesis of 1-(Hydroxyamino)alkyl(or aryl)phosphonic Acids

Reduction of dialkyl 1-(hydroxyimino)alkyl(aryl)phosphonate 1 with borane-pyridine complex proceeds smoothly to give dialkyl 1-(hydroxyamino) alkyl(or aryl)phosphonate 2 which is then easily converted into the corresponding hydroxyaminophosphonic acid 3 by acidic hydrolysis.