@article {2278,
	title = {Accurate calculation of N1s and C1s core electron binding energies of substituted pyridines. Correlation with basicity and with Hammett substituent constants},
	journal = {Journal of Molecular Structure-Theochem},
	volume = {863},
	number = {1-3},
	year = {2008},
	note = {ISI Document Delivery No.: 342NSTimes Cited: 6Cited Reference Count: 23Takahata, Yuji Wulfman, Carl E. Chong, Delano P.},
	month = {Aug},
	pages = {33-38},
	type = {Article},
	abstract = {Substituent shifts of the energetics of four related ionization processes of pyridines and benzoic acids (Fig. I) were investigated. The first process is core-electron ionization of gas-phase pyridines (Fig. 1A), while the second concerns gas-phase acid-base reaction between a substituted pyridine and a Conjugated acid (Fig. 1B), and the third and fourth processes are the acid dissociation of substituted benzoic acids in aqueous solution (Fig. 1C and in vacuum (Fig. 1D), respectively. Core-electron binding energies for the first process Were Calculated using density-functional theory with the scheme Delta E-KS (PW86x-PW91c/TZP+C-ret)//HF/6-31G*. Average absolute deviation of calculated core electron binding energy shifts at N atom in Substituted pyridines from experiment was 0.08 eV. The shift at N coincides highly with that at a ring carbon atom. The four shifts corresponding to the four processes shown in Figs. 1A-D correlate strongly with one another. with numerical values fairly close to each other when expressed in unit of electron volts. (C) 2008 Elsevier B.V. All rights reserved.},
	keywords = {acid dissociation, BENZENE-DERIVATIVES, CEBE shifts, DENSITY-FUNCTIONAL CALCULATION, DFT, Hammett substituent (sigma) constant, ionization processes, PARAMETERS, pyridines, SHIFTS, SIGMA CONSTANTS, SPECTROSCOPY},
	isbn = {0166-1280},
	url = {<Go to ISI>://000258791400006},
	author = {Takahata, Y. and Wulfman, C. E. and Chong, D. P.}
}
@article {1592,
	title = {Conformational stability, molecular structure, and intramolecular hydrogen bonding of thenoyltrifluoroacetone},
	journal = {J. Theor. Comput. Chem.},
	volume = {5},
	number = {3},
	year = {2006},
	note = {ISI Document Delivery No.: 098FUTimes Cited: 3Cited Reference Count: 52Tayyari, Sayyed Faramarz Nekoei, Abdo-Reza Vakili, Mohammad Hassanpour, Masoud Wang, Yan Alexander},
	month = {Sep},
	pages = {647-664},
	type = {Article},
	abstract = {<p>Complete conformational analysis of all possible keto and enol forms of thenoyltrifluoroacetone (TTFA) was carried out using density functional theory with the B3LYP functional and the 6-31G**, 6-311G**, and 6-311++G** basis sets. In addition, the geometries and energies of the four most stable chelated conformers and their corresponding open structures were obtained at the MP2/6-31G** level of theory. The energy differences between the four stable chelated enol conformers, in the gas phase, calculated at the B3LYP levels are negligible. However, calculations at the MP2 level indicate that the B2 conformer (the hydroxyl group in the -CF3 side) is significantly more stable than others, in agreement with the X-ray diffraction results. The calculated intramolecular hydrogen bond (IHB) energy E-HB and the strength of the bond have been compared, and an imperfection in the prevalent method of evaluating E-HB has been perceived. The IHB of TTFA was compared with those in several beta-dicarbonyls.</p>},
	keywords = {ACETYLACETONE, beta-diketone, BETA-DIKETONES, conformational analysis, CRYSTAL-STRUCTURE, EQUILIBRIUM CONSTANTS, INFRARED-SPECTRA, intramolecular hydrogen bond, KETO-ENOL-TAUTOMERISM, nuclear magnetic resonance, PROTON CHEMICAL, SHIFTS, SYNERGISTIC EXTRACTION, thenoyltrifluoroacetone, VIBRATIONAL ASSIGNMENT},
	isbn = {0219-6336},
	url = {<Go to ISI>://000241507200011},
	author = {S. F. Tayyari* and A.-R. Nekoei and Vakili, M. and Hassanpour, M. and Wang, Y. A.}
}
@article {1585,
	title = {DFT calculation of core-electron binding energies of pyrimidine and purine bases},
	journal = {International Journal of Quantum Chemistry},
	volume = {106},
	number = {13},
	year = {2006},
	note = {ISI Document Delivery No.: 082IQTimes Cited: 12Cited Reference Count: 12Takahata, Yuji Okamoto, Andre K. Chong, Delano P.13th Brazilian Symposium of Theoretical ChemistryNOV 20-23, 2005Sao Pedro, BRAZILNatl Res Council, CAPES, Rede Nanotecnol Mole \& Interfaces, FAPESP, FAPERJ, FAPDFSp. Iss. SI},
	month = {Nov},
	pages = {2581-2586},
	type = {Proceedings Paper},
	abstract = {We calculated the accurate core-electron binding energies (CEBEs) of pyrimidine and purine bases in their isolated forms in the gas phase, i.e., uracil (U), thymine (T), cytosine (C), adenine (A), and guanine (G), using density functional theory (DFT) with the scheme Delta E (PW86-PW91)/TZP//HF/6-31G*. The relative magnitude of calculated CEBEs of the same type of atom in the gas phase pyrimidine and purine bases reflect its chemical environment. Comparison between the calculated CEBEs of the bases in the gas phase and observed CEBEs of the same molecules in the solid state permitted estimation of the approximate work functions (WD). Using the approximate WD, it was possible to calculate approximate CEBEs of the DNA bases in the solid state. The average absolute deviation from experiment was 0.37 eV. (C) 2006 Wiley Periodicals, Inc.},
	keywords = {ACCURATE, CEBE, DFT, DNA bases, ESCA, SHIFTS},
	isbn = {0020-7608},
	url = {<Go to ISI>://000240380400006},
	author = {Takahata, Y. and Okamoto, A. K. and Chong, D. P.}
}
@article {3926,
	title = {Cationic lanthanide complexes of N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetic acid (H(2)bped)},
	journal = {Inorganic Chemistry},
	volume = {36},
	number = {7},
	year = {1997},
	note = {ISI Document Delivery No.: WQ490Times Cited: 22Cited Reference Count: 51},
	month = {Mar},
	pages = {1316-1321},
	type = {Article},
	abstract = {A series of monocationic lanthanide complexes containing the ligand N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetate(2-) (bped(2-)) have been prepared and isolated as either the hexafluorophosphate or perchlorate salts. The complexes have been characterized by H-1 and C-13 NMR, +LSIMS, IR, and elemental analysis. Complex formation constants have been measured in water at 25 degrees C (mu = 0.16 M (NaCl)). log K (Ln(bped)](+)) (log K([Ln(bped)(OH)])): Ln = La, 10.81 (0.06); Ln = Nd, 11.99 (1.45); Ln = Gd, 12.37 (2.10); Ln = Ho, 12.31 (3.00); Ln = Yb, 13.32 (4.43). The stability constants for [M(bped)](+) increase from La(III) to Nd(III), plateau to Ho(III), and increase again to Yb(III), while the formation constants for [Ln(bped)(OH)] increase almost linearly with atomic number. The solution structures of the [Ln(bped)](+) complexes have been probed by multinuclear NMR (H-1, C-13, O-17) studies, and these indicate only one isomer present in solution; this isomer has 2-fold symmetry and is rigid at 20 degrees C on the NMR time scale. O-17 NMR studies of the paramagnetic lanthanides indicate that the hydration number is 3, [Ln(bped)(H2O)(2)](+), and that an overall coordination number of 9 is maintained across the lanthanide series.},
	keywords = {AQUEOUS-SOLUTION, CARBOXYLATES, COMPLEXES, COORDINATION-NUMBER, EDTA, GADOLINIUM(III), NMR, NUCLEAR MAGNETIC-RESONANCE, polarization, SHIFT-REAGENTS, SHIFTS, WATER-MOLECULES},
	isbn = {0020-1669},
	url = {<Go to ISI>://A1997WQ49000007},
	author = {Caravan, P. and Mehrkhodavandi, Parisa and Orvig, Chris}
}
@article {3926,
	title = {Cationic lanthanide complexes of N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetic acid (H(2)bped)},
	journal = {Inorganic Chemistry},
	volume = {36},
	number = {7},
	year = {1997},
	note = {ISI Document Delivery No.: WQ490Times Cited: 22Cited Reference Count: 51},
	month = {Mar},
	pages = {1316-1321},
	type = {Article},
	abstract = {A series of monocationic lanthanide complexes containing the ligand N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetate(2-) (bped(2-)) have been prepared and isolated as either the hexafluorophosphate or perchlorate salts. The complexes have been characterized by H-1 and C-13 NMR, +LSIMS, IR, and elemental analysis. Complex formation constants have been measured in water at 25 degrees C (mu = 0.16 M (NaCl)). log K (Ln(bped)](+)) (log K([Ln(bped)(OH)])): Ln = La, 10.81 (0.06); Ln = Nd, 11.99 (1.45); Ln = Gd, 12.37 (2.10); Ln = Ho, 12.31 (3.00); Ln = Yb, 13.32 (4.43). The stability constants for [M(bped)](+) increase from La(III) to Nd(III), plateau to Ho(III), and increase again to Yb(III), while the formation constants for [Ln(bped)(OH)] increase almost linearly with atomic number. The solution structures of the [Ln(bped)](+) complexes have been probed by multinuclear NMR (H-1, C-13, O-17) studies, and these indicate only one isomer present in solution; this isomer has 2-fold symmetry and is rigid at 20 degrees C on the NMR time scale. O-17 NMR studies of the paramagnetic lanthanides indicate that the hydration number is 3, [Ln(bped)(H2O)(2)](+), and that an overall coordination number of 9 is maintained across the lanthanide series.},
	keywords = {AQUEOUS-SOLUTION, CARBOXYLATES, COMPLEXES, COORDINATION-NUMBER, EDTA, GADOLINIUM(III), NMR, NUCLEAR MAGNETIC-RESONANCE, polarization, SHIFT-REAGENTS, SHIFTS, WATER-MOLECULES},
	isbn = {0020-1669},
	url = {<Go to ISI>://A1997WQ49000007},
	author = {Caravan, P. and Mehrkhodavandi, Parisa and Orvig, Chris}
}
@article {4020,
	title = {Complete measurement of the pK(a) values of the carboxyl and imidazole groups in Bacillus circulans xylanase},
	journal = {Protein Science},
	volume = {6},
	number = {12},
	year = {1997},
	note = {ISI Document Delivery No.: YK912Times Cited: 44Cited Reference Count: 29},
	month = {Dec},
	pages = {2667-2670},
	type = {Article},
	abstract = {Electrostatic interactions in proteins can be dissected experimentally by determining the pK(a), values of their constituent ionizable amino acids. To complement previous studies of the glutamic acid and histidine residues in Bacillus circulans xylanase (BCX), we have used NMR methods to measure the pK(a)s of the seven aspartic acids and the C-terminus of this protein. The pK(a)s of these carboxyls are all less than the corresponding values observed with random coil polypeptides, indicating that their ionization contributes favorably to the stability of the folded enzyme. In general, the aspartic acids with the most reduced pK(a)s are those with limited exposure to the solvent and a high degree of conservation among homologous xylanases. Most dramatically, Asp 53 and Asp 101 have pK(a)s < 2 and thus remain deprotonated in native BCX under all conditions examined. Asp 83 is completely buried, forming a strong salt bridge with Arg 136. In contrast, Asp 101 is located on the surface of the protein, stabilized in the deprotonated form by an extensive network of hydrogen bonds involving an internal water molecule and the neutral side-chain and main-chain atoms of Ser 100 and Thr 145. These data provide a complete experimental database for theoretical studies of the ionization behavior of BCX under acidic conditions.},
	keywords = {aspartic acid, electrostatics, FAMILIES, NMR, NMR ASSIGNMENTS, NUCLEAR-MAGNETIC-RESONANCE, PK(A), PROTEINS, RESIDUES, SHIFTS, titration, XYLANASE},
	isbn = {0961-8368},
	url = {<Go to ISI>://A1997YK91200024},
	author = {Joshi, M. D. and Hedberg, A. and McIntosh, L. P.}
}
