Advances in Photochemistry: Volume 6

Advances in Photochemistry: Volume 6 , W. A. NOYES, Jr., G. S. HAMMOND and J. N. Pins, Jr. (Editors).     

BOOK REVIEW

Book reviewed in this article:
Advances in Photochemistry, Vol. 10. Edited by J. N. Pitts, Jr., G. S. Hammond and K. Gollnick.     

BOOK REVIEWS

Book reviewed in this article:
Advances in Radiation Biology, Editors: J. T. Lett and H. Adler,
Advances in Photochemistry. Vol. 9. Edited by J. N. Pitts, Jr., G. S. Hammond, and K. Gollnick.     

Stability, reactivity, and aromaticity of compounds of a multivalent superatom

In this article, we analyze the stability, reactivity, and possible aromatic behavior of two recently reported clusters (Reveles, J. U.; Khanna, S. N.; Roach, P. J.; Castleman, A. W., Jr. Proc. Natl. Acad. Sci. 2006, 103, 18405), viz., Al(7)C(-) and Al(7)O(-) in the light of the principles of the maximum hardness and minimum electrophilicity as well as the nucleus-independent chemical shift values. Stability of these clusters in the context of addition/removal of an electron or an Al atom is now clearly understood.     

Two-state reactivity in alkane hydroxylation by non-heme iron-oxo complexes

Density functional theory is used to explore the mechanisms of alkane hydroxylation for four synthetic non-heme iron(IV)-oxo complexes with three target substrates (Kaizer, J.; Klinker, E. J.; Oh, N. Y.; Rohde; J.-U.; Song, W. J.; Stubna, A.; Kim, J.; Münck, E.; Nam, W.; Que, L., Jr. J. Am. Chem. Soc. 2004, 126, 472-473; Rohde, J.-U.; Que, L., Jr. Angew. Chem. Int. Ed. 2005, 44, 2255-2258.). The iron-oxo reagents possess triplet ground states and low-lying quintet excited states. The set of experimental and theoretical reactivity trends can be understood if the reactions proceed on the two spin states, namely two-state reactivity (TSR); an appropriate new model is presented. The TSR model makes testable predictions: (a) If crossing to the quintet state occurs, the hydroxylation will be effectively concerted; however, if the process transpires only on the triplet surface, stepwise hydroxylation will occur, and side products derived from radical intermediates would be observed (e.g., loss of stereochemistry). (b) In cases of crossing en route to the quintet transition state, one expects kinetic isotope effects (KIEs) typical of tunneling. (c) In situations where the two surfaces contribute to the rate, one expects intermediate KIEs and radical scrambling patterns that reflect the two processes. (d) Solvent effects on these reactions are expected to be very large.     

New Regional Editor – Prof. Valter José Fernandes, Jr.

Introduction

New Regional Editor – Prof. Valter José Fernandes, Jr.     

Ab initio calculations of nitrogen oxide reactions: formation of N2O2, N2O3, N2O4, N2O5, and N4O2 from NO, NO2, NO3, and N2O

Ab initio computational methods were used to obtain Delta(r)H(o), Delta(r)G(o), and Delta(r)S(o) for the reactions 2 NO <=> N(2)O(2) (I), NO+NO(2) <=> N(2)O(3) (II), 2 NO(2) <=> N(2)O(4) (III), NO(2)+NO(3) <=> N(2)O(5) (IV), and 2 N(2)O <=> N(4)O(2) (V) at 298.15 K. Optimized geometries and frequencies were obtained at the CCSD(T) level for all molecules except for NO, NO(2), and NO(3), for which UCCSD(T) was used. In all cases the aug-cc-pVDZ (avdz) basis set was employed. The electronic energies of all species were obtained from complete basis set extrapolations (to aug-cc-pV5Z) using five different extrapolation methods. The [U]CCSD(T)/avdz geometries and frequencies of the N(x)O(y) compounds are compared with literature values, and problems associated with the values and assignments of low-frequency modes are discussed. The standard entropies are compared with values cited in the NIST/JANAF tables [NIST-JANAF Thermochemical Tables, J. Phys. Chem. Ref. Data Monograph No. 9, 4th ed. edited by M. W. Chase, Jr. (American Chemical Society and American Institute of Physics, Woodbury, NY, 1988)]. With the exception of I, in which the dimer is weakly bound, and V, for which thermodynamic data appears to be lacking, the calculated standard thermodynamic functions of reaction are in good agreement with literature values obtained both from statistical mechanical and various equilibrium methods. A multireference-configuration interaction calculation (MRCI+Q) for I provides a D(e) value that is consistent with previous calculations. The combined uncertainties of the NIST/JANAF values for Delta(r)H(o), Delta(r)G(o), and Delta(r)S(o) of II, III, and IV are discussed. The potential surface for the dissociation of N(2)O(4) was explored using multireference methods. No evidence of a barrier to dissociation was found.     

Book Reviews

Ion-Selective Electrodes in Analytical Chemistry, VOL. 2, H. Freiser (ed.), Plenum Press, New York, 1980.

Pesticide Analytical Methodology by John Harvey, Jr. (E. I. Du Pont de Nemours and Company) and Gunter Zweig (U.S. Environmental Protection Agency), ACS Symposium Series 136, 406 pages (including 177 figures, 54 tables and an index of 18 pages), linen, format 235 × 160mm, ISBN 0-8412-0581-7, American Chemical Society, 1155 Sixteenth Street, N.W. Washington, D.C. 20036, 1980, US38.00.

Particulates in Water, Characterization, Fate, Effects, and Removal by Michael C. Kavanaugh (James M. Montgomery, Consulting Engineers, Inc., Pasadena) and James O. Leckie (Stanford University, Stanford) ACS Advances in Chemistry Series 189, 401 pages (including 145 figures, 56 tables and an index of 11 pages), linen, format 235 × 160mm, ISBN 0-8412-0499-3, American Chemical Society, 1155 Sixteenth Street, N.W. Washington, D.C. 20036, 1980, USS59.50.

Pesticide Manufacturing and Toxic Materials Control Encyclopedia Editor, M. Sittig; 810 pages, $96; 1980, Noyes Data Corporation, Park Ridge, N.J., U.S.A. ISBN 0-8155-0814-X. Reviewed by A. de Kok, Section of Environmental Chemistry, Free University, Amsterdam, The Netherlands.

Dictionary of Chemical Terminology (In Five Languages–English, German, French, Polish and Russian. Edited by D. Kryt, Warsaw, Poland). Elsevier Scientific Publishing Company, Amsterdam and New York. 1980, 612 pages, Price: US $95.00/Dfl. 195.00 ISSBN 0-444-99788-1.     

Cover Picture: Angew. Chem. Int. Ed. 9/2002

The cover picture shows adamantane‐2,6‐dione encapsulated within a hydrogen‐bonded capsule made up of four identical subunits. The ketone functionality of the guest molecule (CPK model, red) participates in the structural seam at each end of the capsule through bifurcated hydrogen bonds. Find out more about encapsulating complexes in the review by Rebek, Jr., et al. on p. 1488 ff.     

The Relationship of William Henry Perkin,Jr. and Sir Robert Robinson: Teacher and Student,then Student and Teacher

William Henry Perkin, Jr. FRS, the son of the inventor of mauve and other commercial dyes and credited for initiating the industrialization of chemistry, was himself a notable chemist. He was the Professor of Organic Chemistry at Manchester from 1892–1912 and then was the Waynflete Professor of Chemistry at Oxford and the first Head of the Dyson Perrins Laboratory from 1912–1929. One of Perkin's graduate students and research assistants at Manchester was Robert Robinson, subsequently Sir Robert Robinson, FRS and recipient of the 1947 Nobel Prize in Chemistry. Perkin and Robinson had perhaps the most productive and broad collaboration between a professor and one's student. Together, during and after Robinson's student days, they had 71 joint publications, 25 of which involved just the two of them, 17 of which involved the structure determination of strychnine, and eight of which were published after Perkin's death in 1929. Upon Perkin's early death, Robinson succeeded him as the fourth Waynflete Professor of Chemistry at the Dyson Perrins Laboratory, Oxford University. This Essay will examine the professional relationship of Perkin, Jr. and Robinson as revealed in their joint publications on the structure of strychnine.     

Kinetic analysis of the reaction between (V2O5)n=1,2+ and ethylene

A systematic experimental and theoretical investigation of the influence of reactant energy on the reactivity of (V(2)O(5))(n)=1,2(+) clusters with ethylene (Justes, D. R.; Mitri?, R.; Moore, N. A.; Bonaci?-Koutecky, V.; Castleman, A. W., Jr. J. Am. Chem. Soc., 2003, 125, 6289) provided evidence of the rate controlling steps in the reaction. Herein, we present further experimental and theoretical evidence for our recently proposed radical cation mechanism for oxygen atom transfer from (V(2)O(5))(n)=1,2(+) clusters to ethylene. In particular the results of ab initio molecular dynamics simulations are found to further support the radical cation mechanism. Experimental reaction cross sections at the zero pressure limit and rate coefficients show that the energy dependence of the reaction cross section is in accord with the Langevin formula. Evidence is presented that ion-molecule association is the rate determining step, whereas subsequent hydrogen transfer and formation of acetaldehyde proceed without significant barriers. We propose a kinetic model for the reaction cross section that fully accounts for the experimental findings. The model offers the prospect of elucidating the details of the general reaction mechanisms through a study of the energy dependence of the reaction cross sections.     

Persuading the Non-canonical Intercalated-Motif DNA to Reveal Its Structure

This invited Team Profile was created by Kevin Li and Liliya Yatsunyk, Swarthmore College PA (USA) and by John Schneekloth, Jr, (Jay) National Cancer Institute, Frederick MD (USA) . They recently published an article on the first crystal structure of an intercalated motif (i-motif or iM) from the HRAS oncogene involved in many cancers. The iHRAS structure was solved to 1.8 Å resolution. It contains a tail-to-tail dimer of two iMs each with six C−C⁺ base pairs. The structure is unique in that only two base pairs out of 20 are canonical. The extensive network of capping and connecting interactions is unprecedented. The unique structural elements (loops/connecting region) may be targeted by ligands or proteins as cancer therapies. iHRAS represents the first crystallized iM-forming structure from a human promoter. “Crystal Structure of an iM from the HRAS Oncogene Promoter”, K. S. Li, D. Jordan, L. Y. Lin, S. E. McCarthy, J. S. Schneekloth Jr., and L. A. Yatsunyk, Angew. Chem. Int. Ed. Engl. 2023 , 62, e202301666 .     

Book Review: Ion mobility spectrometry, 3rd ed. by G.A. Eiceman,Z. Karpas and H.H. Hill,Jr.

After the first edition, released in 1994 and 228 pages long, followed by the second edition, published in 2005 and now 350 pages in length, CRC press (Taylor & Francis Group, Boca Raton, FL) has now released the third edition of Ion mobility spectrometry at the beginning of this year. The content has been expanded to 428 pages and Herbert H. Hill Jr. is now onboard, working alongside the previous authors Gary Eiceman and Zeev Karpas.     

Electronic structure and spectroscopy of "superoxidized" iron centers in model systems: theoretical and experimental trends

Recent advances in synthetic chemistry have led to the discovery of "superoxidized" iron centers with valencies Fe(v) and Fe(vi) [K. Meyer et al., J. Am. Chem. Soc., 1999, 121, 4859-4876; J. F. Berry et al., Science, 2006, 312, 1937-1941; F. T. de Oliveira et al., Science, 2007, 315, 835-838.]. Furthermore, in recent years a number of high-valent Fe(iv) species have been found as reaction intermediates in metalloenzymes and have also been characterized in model systems [C. Krebs et al., Acc. Chem. Res., 2007, 40, 484-492; L. Que, Jr, Acc. Chem. Res., 2007, 40, 493-500.]. These species are almost invariably stabilized by a highly basic ligand X(n-) which is either O(2-) or N(3-). The differences in structure and bonding between oxo- and nitrido species as a function of oxidation state and their consequences on the observable spectroscopic properties have never been carefully assessed. Hence, fundamental differences between high-valent iron complexes having either Fe=O or Fe=N multiple bonds have been probed computationally in this work in a series of hypothetical trans-[FeO(NH(3))(4)OH](+/2+/3+) (1-3) and trans-[FeN(NH(3))(4)OH](0/+/2+) (4-6) complexes. All computational properties are permeated by the intrinsically more covalent character of the Fe=N multiple bond as compared to the Fe=O bond. This difference is likely due to differences in Z* between N and O that allow for better orbital overlap to occur in the case of the Fe=N multiple bond. Spin-state energetics were addressed using elaborate multireference ab initio computations that show that all species 1-6 have an intrinsic preference for the low-spin state, except in the case of 1 in which S=1 and S=2 states are very close in energy. In addition to M?ssbauer parameters, g-tensors, zero-field splitting and iron hyperfine couplings, X-ray absorption Fe K pre-edge spectra have been simulated using time-dependent DFT methods for the first time for a series of compounds spanning the high-valent states +4, +5, and +6 for iron. A remarkably good correlation of these simulated pre-edge features with experimental data on isolated high-valent intermediates has been found, allowing us to assign the main pre-edge features to excitations into the empty Fe d(z(2)) orbital, which is able to mix with Fe 4p(z), allowing an efficient mechanism for the intensification of pre-edge features.     

Photodissociation of (SO2)m(H2O)n clusters employing femtosecond pump-probe spectroscopy

A femtosecond pump-probe technique was employed to study the photodissociation dynamics of (SO2)m(H2O)n clusters in real time for clusters, where m=1, 2 and n as large as 11. The pump (excitation) step occurs through a multiphoton process which populates the dissociative E state as well as a lower-lying bound state of the sulfur dioxide (SO2) chromophore. Dissociation of the SO2 monomer occurs through the E state and the decay is fit to a lifetime of 230 fs. The present study is in agreement with our previous investigations of homogeneous (SO2)m clusters that have shown that cluster formation inhibits the dissociation process owing to a steric effect induced by the cluster environment [K. L. Knappenberger, Jr. and A. W. Castleman, Jr., J. Chem. Phys. 121, 3540 (2004)]. The E state lifetime increases sequentially as a function of cluster size to as much as 668 fs when 11 water molecules solvate the chromophore. We have employed a method to compare the ratio of amplitude coefficients, which reflect a respective component of the mathematical fit, to determine the nature of the wave packet evolution in binary clusters. An increase of this ratio by as much as 440% was observed for large cluster sizes. A preferential ion state charge transfer, rather than dissociation, was observed in binary clusters. The significance of cluster size on evaporation processes has been investigated.     

Commentary: Reflections on “interfacial polycondensation. I.,” by Emerson L. Wittbecker and Paul W. Morgan,J. Polym. Sci., XL, 289 (1959)

The book, Science and Corporate Strategy: DuPont R&D, 1902–1980, by David A. Hounshell and John Kelly Smith, Jr., and published by Cambridge University Press (1988) was used as a source for some of the information in this perspective of polymer research before and during the exploration of interfacial polycondensation. Dacron® and Lycra® are trademarks of the E. I. DuPont Company for its polyester and spandex fibers. Nomex® and Kevlar® are trademarks for its aramid fibers.     

Vibrational analysis of mononitrosyl complexes in hemerythrin and flavodiiron proteins: relevance to detoxifying NO reductase

Flavodiiron proteins (FDPs) play important roles in the microbial nitrosative stress response in low-oxygen environments by reductively scavenging nitric oxide (NO). Recently, we showed that FMN-free diferrous FDP from Thermotoga maritima exposed to 1 equiv NO forms a stable diiron-mononitrosyl complex (deflavo-FDP(NO)) that can react further with NO to form N(2)O [Hayashi, T.; Caranto, J. D.; Wampler, D. A; Kurtz, D. M., Jr.; Mo?nne-Loccoz, P. Biochemistry 2010, 49, 7040-7049]. Here we report resonance Raman and low-temperature photolysis FTIR data that better define the structure of this diiron-mononitrosyl complex. We first validate this approach using the stable diiron-mononitrosyl complex of hemerythrin, Hr(NO), for which we observe a ν(NO) at 1658 cm(-1), the lowest ν(NO) ever reported for a nonheme {FeNO}(7) species. Both deflavo-FDP(NO) and the mononitrosyl adduct of the flavinated FPD (FDP(NO)) show ν(NO) at 1681 cm(-1), which is also unusually low. These results indicate that, in Hr(NO) and FDP(NO), the coordinated NO is exceptionally electron rich, more closely approaching the Fe(III)(NO(-)) resonance structure. In the case of Hr(NO), this polarization may be promoted by steric enforcement of an unusually small FeNO angle, while in FDP(NO), the Fe(III)(NO(-)) structure may be due to a semibridging electrostatic interaction with the second Fe(II) ion. In Hr(NO), accessibility and steric constraints prevent further reaction of the diiron-mononitrosyl complex with NO, whereas in FDP(NO) the increased nucleophilicity of the nitrosyl group may promote attack by a second NO to produce N(2)O. This latter scenario is supported by theoretical modeling [Blomberg, L. M.; Blomberg, M. R.; Siegbahn, P. E. J. Biol. Inorg. Chem. 2007, 12, 79-89]. Published vibrational data on bioengineered models of denitrifying heme-nonheme NO reductases [Hayashi, T.; Miner, K. D.; Yeung, N.; Lin, Y.-W.; Lu, Y.; Mo?nne-Loccoz, P. Biochemistry 2011, 50, 5939-5947 ] support a similar mode of activation of a heme {FeNO}(7) species by the nearby nonheme Fe(II).     

Characterization of the ionization and spectral properties of sulfonephthalein indicators. Correlation with substituent effects and structural features. Part II

A spectrophotometric study is presented on the first ionization equilibrium of a class of substituted sulfonephthaleins, whose second ionization was the subject of the first part of this work. The present study was more difficult than the previous in that highly acid media and acidity functions had to be used. Nevertheless the results were of sufficient accuracy to allow the dual substituent analysis of Swain and Lupton (C.G. Swain and A.C. Lupton, Jr., J. Am. Chem. Soc., 90 (1968) 4328). Generally speaking, the dependences of equilibrium and spectral parameters on field and resonance parameters found in this and the previous paper were very similar.     

Inductive Effects on the Energetics of Prolyl Peptide Bond Isomerization: Implications for Collagen Folding and Stability

The hydroxylation of proline residues in collagen enhances the stability of the collagen triple helix. Previous X-ray diffraction analyses had demonstrated that the presence of an electron-withdrawing substituent on the pyrrolidine ring of proline residues has significant structural consequences [Panasik, N., Jr.; Eberhardt, E. S.; Edison, A. S.; Powell, D. R.; Raines, R. T. Int. J. Pept. Protein Res.1994, 44, 262-269]. Here, NMR and FTIR spectroscopy were used to ascertain kinetic and thermodynamic properties of N-acetyl-[β,γ-(13)C]D,L-proline methylester (1); N-acetyl-4(R)-hydroxy-L-proline [(13)C]methylester (2); and N-acetyl-4(R)-fluoro-L-proline methylester (3). The pK(a)'s of the nitrogen atom in the parent amino acids decrease in the order: proline (10.8) > 4(R)-hydroxy-L-proline (9.68) > 4(R)-fluoro-L-proline (9.23). In water or dioxane, amide I vibrational modes decrease in the order: 1 > 2 > 3. At 37 °C in dioxane, the rate constants for amide bond isomerization are greater for 3 than 1. Each of these results is consistent with the traditional picture of amide resonance coupled with an inductive effect that results in a higher bond order in the amide C=O bond and a lower bond order in the amide C-N bond. Further, at 37 °C in water or dioxane equilibrium concentrations of the trans isomer increase in the order: 1 < 2 < 3. Inductive effects may therefore have a significant impact on the folding and stability of collagen, which has a preponderance of hydroxyproline residues, all with peptide bonds in the trans conformation.     

Microscopic observation of the crystalline form of poly(<Emphasis Type="Italic">o</Emphasis>-methoxyaniline) on a membrane electrode

We describe electrochemical and microscopic (SEM) studies on the electrochemical polymerization of poly(o-methoxyaniline). The crystalline form of the polymer was obtained. The poly(o-methoxyaniline) crystals are formed on a membrane electrode from an acidic solution of the monomer. It is suggested that the pores of the membrane work as nuclear crystallization points.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)