41751-82-0Relevant academic research and scientific papers
Separation of contributions to the third-order signal: Ultrafast frequency-selected vibrational echo experiments on a metalloporphyrin-CO
Xu, Qing-Hua,Thompson, David E.,Merchant,Fayer
, p. 139 - 146 (2002)
One-dimensional and frequency-selected vibrational echo experiments on the CO stretching mode of a metalloporphyrin carbonyl compound (model heme) in poly-methylmethacrylate (PMMA) and in 2-methylteterahydrofuran (2-MTHF) are compared. Spectrally resolving the vibrational echo signal and observing the decay at selected wavelengths, permits the independent detection of the 0-1 and 1-2 vibrational level dephasing dynamics, eliminating cross terms and anharmonic beats. In the high temperature 2-MTHF liquid, 0-1 and 1-2 dephasing dynamics are identical within experimental error. The decays are non-exponential, demonstrating that the CO stretching mode absorption spectrum is not a completely homogeneous, motionally narrowed line.
Synthesis of calix[4]arene-bis(tin(IV)porphyrins) and supramolecular complexes on their basis
Mamardashvili,Chizhova,Mamardashvili
, p. 390 - 397 (2012/07/02)
Selective substitution of one of the two trans hydroxy groups of calix[4]arene-bis(porphyrinato-tin(IV)) resulted in supramolecular tetramer assemblies based thereon with parallel and perpendicular arrangement of tetrapyrrole macrocyclic rings, which were characterized by UV spectroscopy, 1H NMR, and elemental analysis data.
Synthetic and mechanistic aspects of a new method for ruthenium-metalation of porphyrins and Schiff-bases
Reboucas, Julio S.,Cheu, Elizabeth L. S.,Ware, Caroline J.,James, Brian R.,Skov, Kirsten A.
, p. 7894 - 7907 (2009/02/08)
A new method is presented for metalation of a wide range of free-base, neutral, cationic, and anionic porphyrins in refluxing dimethylformamide (DMF) using an easily prepared [Ru(DMF)6](OTf)3 complex, and comparisons are made with the more familiar metalation procedure using Ru 3(CO)12. Both procedures generate RuII(porp) (CO)L complexes (L = solvent); use of the RuIII-triflate precursor gives yields comparable to, or greater than, those obtained with the carbonyl, and generates no Ru-chlorin impurities. Mechanistic studies on the meso-tetraphenylporphyrin system reveal that the DMF furnishes the CO, which in the presence of essential water reduces the metal, and metalation likely occurs via a RuII-CO species. Corresponding metalation of tetradentate Schiff-bases gives trans-[RuIII(Schiff- base)(DMF)2]OTf complexes in yields of ～50%, a limitation being the accompanying hydrolysis of the Schiff-base through the presence of trace water.
Frequency selected ultrafast infrared vibrational echo studies of liquids, glasses, and proteins
Merchant,Xu, Qing-Hua,Thompson, David E.,Fayer
, p. 8839 - 8849 (2007/10/03)
Ultrafast infrared frequency selected vibrational echo (FSVE) was discussed. FSVE is used to study temperature-dependent dynamic interactions in liquids, glasses and proteins. Results showed that FSVE hepls in detecting the dephasing dynamics associated w
Axial-Ligand Control of the Photophysical Behavior of Ruthenium(II) Tetraphenyl- and Octaethylporphyrin. Contrasting Properties of Metalloporphyrin (?,?*) and (d,?*) Excited States
Levine, Leanna M. A.,Holten, Dewey
, p. 714 - 720 (2007/10/02)
The photophysical behavior of the ruthenium(II) porphyrins depends dramatically on the axial ligands coordinated to the central metal ion.We have measured the picosecond and slower time scale transient absorption spectra and kinetics, emission data, and ground-state absorption spectra for two classes of complexes: RuP(CO)(L) and RuP(L)2.Results are compared for complexes in which the porphyrin macrocycle (P) is tetraphenylporphyrin (TPP) or octaethylporphyrin (OEP) and the axial ligand L is piperidine (pip), pyridine (py), dimethyl sulfoxide (Me2SO), or ethanol (EtOH).We assign the lowest excited state of all the RuP(CO)(L) complexes, including those with L absent, as the lowest excited triplet state 3(?,?*), of the porphyrin ring 3(?,?*) appears to form in high yield from the ring excited singlet, 1(?,?*), in a metal-to-ring (d,?*) charge-transfer (CT) state.We attribute this general switch of the lowest excited state from 3(?,?*) in RuP(CO)(L) to (d,?* in RuP(L)2 to the loss of ?-backbonding between the filled Ru(d?) orbitals and the empty CO(?*) orbitals.The loss of axial ?-backbonding is expected to destabilize the d? orbitals, making them closer in energy to the empty eg(?*) orbitals of the porphyrin ring.This lowers the energy of (d,?*) relative to 3(?,?*) in RuP(L)2 compared to RuP(CO)(L).Although 3(?,?*) appears to be the lowest excited state in all the RuP(CO)(L) complexes investigated, we propose that the deactivation of this state nonetheless proceeds, in part, via a shorter lived (d,?*) state at higher energy.We speculate that the faster decay of (d,?*) compared to 3(?,?*) may be due to a better Franck-Condon factor for radiationless decay to the ground state.The recay route of 3(?.?*) via a thermally accessible (d,?*) in the RuP(CO)(L) complexes also may be the pathway for photodissociation of CO from these molecules, which in the presence of L results in the formation of RuP(L)2.The photodissociation quantum yield is measured to be ca. 1E-4 for two of the complexes.
Investigation of the electrochemical reactivity and axial ligand binding reactions of tetraphenylporphyrin carbonyl complexes of ruthenium(II)
Kadish,Leggett,Chang
, p. 3618 - 3622 (2008/10/08)
Stability constants for nitrogenous base addition to (TPP)Ru(CO) and [(TPP)Ru(CO)]+ were calculated. Spectrophotometric methods were utilized for stability constant determinations of the five-coordinate neutral complex while a combination of spectrophotometric and electrochemical techniques was utilized to calculate values for ligand addition to the cation radical. Twenty different nitrogenous bases were investigated. For (TPP)Ru(CO)(L) values of log β1 ranged from 3.62 to 5.63 and generally increased as a function of the ligand pKa. Values of log β1 for formation of [(TPP)Ru(CO)(L)]+ ranged from 2.40 to 6.63 and also increased with the ligand pKa. Comparisons were made between the measured values of log β1 and reversible potentials for the electrode reaction (TPP)Ru(CO)(L) ? [(TPP)Ru(CO)(L)]+.
Solvent-binding and solvation effects on the electrode reactions of tetraphenylporphyrin carbonyl complexes of ruthenium(II)
Kadish,Chang
, p. 3614 - 3618 (2008/10/08)
The electron-transfer reactions of (5,10,15,20-tetraphenylporphyrin)ruthenium(II) carbonyl, (TPP)Ru(CO), was investigated in 12 nonaqueous solvents. In 10 of these solvents the complex existed in solution as (TPP)Ru(CO)(S), where S is a solvent molecule. This complex could be reversibly oxidized to yield [(TPP)Ru(CO)(S)]+ or reduced to yield [(TPP)Ru(CO)(S)]-. Potentials for the former reactions were related to the Kamlet and Taft β parameter while those for the latter reactions were linearly related to the solvent acceptor number. Stability constants were calculated for addition of each solvent molecule as a sixth axial ligand to (TPP)Ru(CO) in CH2Cl2-0.1 M TBAP. Stability constants for formation of (TPP)Ru(CO)(S) ranged from log β1 = 1.46 for addition of nitromethane to log β1 = 4.63 for pyridine addition. Finally, correlations were made between the stability constants and the spectral properties of each complex.
