Journal•ISSN: 0021-2148

# Israel Journal of Chemistry

Wiley-Blackwell

About: Israel Journal of Chemistry is an academic journal published by Wiley-Blackwell. The journal publishes majorly in the area(s): Chemistry & Catalysis. It has an ISSN identifier of 0021-2148. Over the lifetime, 4185 publications have been published receiving 66769 citations. The journal is also known as: Israel journal of chemistry (Print) & IJC (Weinheim. Print).

Topics: Chemistry, Catalysis, Aqueous solution, Excited state, Electron transfer

##### Papers published on a yearly basis

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TL;DR: In this article, the rate constants of 60 typical electron donor-acceptor systems have been measured in de-oxygenated acetonitrile and are shown to be correlated with the free enthalpy change, ΔG23, involved in the actual electron transfer process.

Abstract: Fluorescence quenching rate constants, kq, ranging from 106 to 2 × 1010 M−1 sec−1, of more than 60 typical electron donor-acceptor systems have been measured in de-oxygenated acetonitrile and are shown to be correlated with the free enthalpy change, ΔG23, involved in the actual electron transfer process
in the encounter complex and varying between + 5 and −60 kcal/mole. The correlation which is based on the mechanism of adiabatic outer-sphere electron transfer requires ΔG≠23, the activation free enthalpy of this process to be a monotonous function of ΔG23 and allows the calculation of rate constants of electron transfer quenching from spectroscopic and electrochemical data.
A detailed study of some systems where the calculated quenching constants differ from the experimental ones by several orders of magnitude revealed that the quenching mechanism operative in these cases was hydrogen-atom rather than electron transfer.
The conditions under which these different mechanisms apply and their consequences are discussed.

3,485 citations

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TL;DR: In this paper, a linear synchronous transit or quadratic synchronous transmisson approach is used to get closer to the quad-ratic region of the transition state and then quasi-newton or eigenvector following methods are used to complete the optimization.

Abstract: A linear synchronous transit or quadratic synchronous transit approach is used to get closer to the quadratic region of the transition state and then quasi-newton or eigenvector following methods are used to complete the optimization. With an empirical estimate of the hessian, these methods converge efficiently for a variety of transition states from a range of starting structures.

1,849 citations

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TL;DR: In this paper, the scaling factors for obtaining fundamental vibrational frequencies and zero-point vibrational energies from harmonic frequencies calculated at the HF/6−31G* and MP2/6-31G*) levels were derived from a comparison of a total of 1066 calculated frequencies for 122 molecules with corresponding experimental values.

Abstract: New scaling factors have been determined for obtaining fundamental vibrational frequencies and zero-point vibrational energies from harmonic frequencies calculated at the HF/6–31G* and MP2/6–31G* levels. The scaling factors for the fundamental frequencies have been derived from a comparison of a total of 1066 calculated frequencies for 122 molecules with corresponding experimental values, while the zero-point energy scaling factors were determined from a comparison of the computed values with the experimental zero-point energies for a set of 24 molecules. The scaling factors recommended are, respectively, 0.8929 and 0.9427 for HF/6–31G* and MP2/6–31G* fundamental frequencies, and 0.9135 and 0.9646 for HF/6–31G* and MP2/6–31G* zero-point energies. RMS errors were determined to be around 50 cm−1 for the HF and MP2 fundamental frequencies, and around 0.4 kJ mol−1 for the HF and MP2 zero-point energies.

765 citations

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TL;DR: A coupled Hartree-Fock theory for diamagnetic susceptibilities χ and chemical shifts σ in terms of localized MO's and individual gauge origins for the different MO's is derived in this paper.

Abstract: A coupled Hartree–Fock theory for diamagnetic susceptibilities χ and chemical shifts σ in terms of localized MO's and individual gauge origins for the different MO's is derived. The new coupled Hartree–Fock equations and expressions for χ and σ differ from the traditional ones by the presence of “exchange coupling terms” (ECT) and “resonance coupling terms” (RCT). For the ECT, that are expected to be very small, a simple approximation is proposed. Both the ECT and the RCT can be decomposed into “diamagnetic” and “paramagnetic” contributions. Spurious paramagnetic terms due to inappropriate choices of the gauge origin are avoided in the present scheme. The possibility to include correlation effects is discussed.

560 citations

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TL;DR: The ConSurF-DB, a new release of which is presented here, provides precalcu- lated ConSurf conservation analysis of nearly all available structures in the Protein DataBank (PDB), as well as a range of large-scale, genome-wide applications.

Abstract: Many mutations disappear from the population because they impair protein function and/or stability. Thus, amino acid positions that are essential for proper function evolve more slowly than others, or in other words, the slow evolutionary rate of a position reflects its importance. Con- Surf (http://consurf.tau.ac.il), reviewed in this manuscript, exploits this to reveal key amino acid positions that are im- portant for maintaining the native conformation(s) of the protein and its function, be it binding, catalysis, transport, etc. Given the sequence or 3D structure of the query protein as input, a search for similar sequences is conducted and the sequences are aligned. The multiple sequence alignment is subsequently used to calculate the evolutionary rates of each amino acid site, using Bayesian or maximum-likelihood algorithms. Both algorithms take into account the evolution- ary relationships between the sequences, reflected in phylo- genetic trees, to alleviate problems due to uneven (biased) sampling in sequence space. This is particularly important when the number of sequences is low. The ConSurf-DB, a new release of which is presented here, provides precalcu- lated ConSurf conservation analysis of nearly all available structures in the Protein DataBank (PDB). The usefulness of ConSurf for the study of individual proteins and mutations, as well as a range of large-scale, genome-wide applications, is reviewed.

493 citations