1613-77-0Relevant academic research and scientific papers
Polar ligand adsorption controls semiconductor surface potentials
Bruening,Moons,Yaron-Marcovich,Cahen,Libman,Shanzer
, p. 2972 - 2977 (1994)
Controlled surface modification of CdTe single crystals and CdTe and CulnSe2 solar cell quality thin films was achieved by chemisorption of a series of organic ligands with varying dipole moments. Contact potential difference measurements in air showed that adsorption of benzoic or hydroxamic acid derivatives on the thin films or crystals changes the semiconductors' electron affinity without significantly affecting band bending. The magnitude and direction of surface potential changes, which reach 670 mV between extreme modifications, correlate with the ligands' dipole moments. Ligand dipole moments were controlled by varying the substituents of the ligand. Quantitative Fourier transform infrared (FTIR) spectroscopy showed that benzoic acid surface coverage is about one monolayer. Finally, FTIR spectral analysis showed that the benzoic acid derivatives adsorb via coordination to Cd on CdTe and that hydroxamic acids bind to Cd on CdTe and to In on CuInSe2. These phenomena occur in several systems (two semiconductor compounds, two types of binding groups, and two types of surface morphologies were examined) and may prove useful in band edge engineering.
Unexpected Z/E isomerism of N-methyl-O-phosphothioyl benzohydroxamic acids, their oxyphilic reactivity and inertness to amines
Majewski, Arkadiusz,Chojnacki, Jaros?aw,Przychodzeń, Witold
, p. 1077 - 1091 (2021/01/11)
Thiophosphinoylation of N-methyl p-substituted benzohydroxamic acids using disulfanes (method A) or diphenylphosphinothioyl chloride (method B) provides only one conformer of the respective O-phosphothioyl derivative (X-ray and NMR analysis). Undergoing t
Oxidative cleavage of hydroxamic acid promoted by sodium periodate
Yuan, Changchun,Du, Biao,Xun, Miao-Miao,Liu, Bo
, p. 3622 - 3628 (2017/06/13)
A series of hydroxamic acids, involving aliphatic, aromatic and cyclic substrates, were transformed to the corresponding carboxylic acids through NaIO4-mediated oxidative cleavage in mild conditions. Esterification of these acids with TMSCHN2 could result in formation of the corresponding methyl ester. This methodology makes good compensation for the existing methods transforming amides to esters. Our results also pave the way to harness hydroxamic acids as useful synthetic building blocks.
Reactivity patterns of N-methylbenzhydroxamates. I. Studies of methyl transfer between N-methylbenzhydroxamates and arenesulfonates
Fountain, Kenneth R.,Fountain, Daniel P.,Michaels, Bernice,Myers, D. Brenton,Salmon, Jon K.,et al.
, p. 798 - 810 (2007/10/02)
The rates of methyl transfer between benzohydroxamates and sulfonates show large βnuc values (ca. 0.8) indicating much charge transfer to the C atom, similar to the results of N,N-dialkylaminofluorene anions.A small α effect shows that even in
Kinetics, mechanism, and thermodynamics of aqueous iron(III) chelation and dissociation: Influence of carbon and nitrogen substituents in hydroxamic acid ligands
Brink, Christina Poth,Crumbliss, Alvin L.
, p. 4708 - 4718 (2008/10/08)
Thermodynamic and kinetic studies were performed to investigate the complexation of aqueous high-spin iron(III) by 12 bidentate hydroxamic acids, R1C(O)N(OH)R2, (R1 = CH3, C6H5, 4-NO2C6H4, 4-CH3C6H4, 4-CH3OC6H4; R2 = CH3, C6H5, 4-CH3C6H4, 4-ClC6H4, 4-IC6H4, 3-IC6H4, 4-NCC6H4, 3-NCC6H4, 4-CH3C(O)C6H4), in acid medium. Both complex formation and dissociation (aquation) reactions were investigated by stopped-flow relaxation methods over a range of [H+] and temperatures. A two-parallel-path mechanism without proton ambiguity is established for the reaction of Fe(H2O)63+ and Fe(H2O)5OH2+ with R1C(O)N(OH)R2 to form Fe(H2O)4(R1C(O)N(O)R2)2+. Equilibrium quotients, ΔH° and ΔS° values, rate constants, and ΔH≠ and ΔS≠ values for both reaction paths in the forward and reverse directions are reported. ΔH≠ and ΔS≠ values are found to be linearly related and compensating. On the basis of an analysis of the equilibrium quotients, rate constants, and activation parameters for the reaction in both directions, an associative interchange (Ia) mechanism is proposed for hydroxamic acid ligand substitution at Fe(H2O)63+. Similar trends for these parameters are observed for the reaction at Fe(H2O)5OH2+, suggesting an associative interchange character for this reaction path also. However, coordinated water dissociation appears to be dominant, and some associative character for this path may be the result of H-bonding interactions between the undissociated hydroxamic acid and coordinated -OH. Electron-donating and -withdrawing R1 and R2 substituents were selected in order to determine the relative influence of the C and N substituent on the hydroxamic acid and to determine the optimum hydroxamic acid structure for kinetic and thermodynamic stability of the iron(III) chelate. Kinetic and thermodynamic chelate stabilization are enhanced by increasing electron density on the carbonyl oxygen atom, which is promoted by electron donors in the R1 position and delocalization of the N atom lone pair of electrons into the C-N bond. The influence of the R2 substituent appears to be dominant with an electron-releasing alkyl group as the preferred R2 substituent for kinetic and thermodynamic stability. The optimum hydroxamic acid ligand for kinetic and thermodynamic stability of the iron(III) chelate was found to be 4-CH3OC6H4C(O)N(OH)CH3.
