peri-Naphthylenediamines. 37. Synthesis of N,N"-diisopropyl-N,N"-dimethyl-1,8-diaminonaphthalene

Alkylation of N,N"-dimethyl-1,8-diaminonaphthalene with 2-iodopropane in a KOH—DMSO system afforded a new proton sponge, viz., N,N"-diisopropyl-N,N"-dimethyl-1,8-diaminonaphthalene; the rotation barrier of the Prⁱ groups about the N—C bond is 68.4±0.4 kJ mol^–1 (DMSO).     

"Alpha"-, "beta"- and "delta"-anhydrodigitoxigenin

The syntheses of 3β-hydroxy-5β-carda-14, 20:22-dienolide (= «β»-anhydro-), 3β-hydroxy-5β-carda-8:14, 20:22-dienolide (= «α»-anhydro-) and «δ»-anhydro-digitoxigenin (= probably 3β-hydroxy-5β, 14β-carda-8, 20:22-dienolide) by the best ways known to date, have been described. «δ»-Anhydro-digitoxigenin represents the thermodynamically most stable isomer. In this isomer the double bond in position 8 is unaffected by hydrogenation with Pt in acetic acid; with perbenzoic acid an epoxide results from which, on hydrogenation, the double bond can be regenerated in its original position. Analogous reactions are known to occur in the 8:14-epoxides.     

Comment on "Optical conversion of conical intersection to avoided crossing" by Y. Arasaki and K. Takatsuka, Phys. Chem. Chem. Phys., 2010, 12, 1239

A recent paper in this journal proposed the conversion of conical intersections to avoided crossings by lowering the symmetry with an optical field. The article also claimed that the characters of nonadiabatic transitions caused by avoided crossings and conical intersections are qualitatively different. The present comment shows that this proposal and this claim result from an incorrect appreciation of the nature of conical intersections and avoided crossings. Conical intersections are moved, not removed, by almost all perturbations. Furthermore, there is no dichotomy between avoided crossing mechanisms and conical intersection mechanisms; as the parameters of the problem change and the typical locally avoided crossing involved in nonadiabatic dynamics becomes farther from the conical intersection, there is a gradual shift in the nature of the nonadiabatic transitions, with a continuum of possible behaviors, not just two.     

Comment on "Multiconfigurational perturbation theory can predict a false ground state" by C. Camacho, R. Cimiraglia and H. A. Witek, Phys. Chem. Chem. Phys., 2010, 12, 5058

Prediction of the true ground state of Sc(2) with multiconfigurational perturbation theory requires a balanced active space in building the reference wave function.     

Spiropyrans and spirooxazines. 2. Synthesis,structures, and photochromic properties of 6"-cyano-substituted spironaphthooxazines

A series of 6"-cyano-substituted spiro[indoline-2,3"-naphtho[2,1-b]oxazines] containing substituents with carbon chains of different lengths in the indoline fragment were synthesized. The structure of one of these spironaphthooxazines was established by X-ray diffraction analysis. The influence of substituents on the photochromic properties of the resulting compounds in solutions and polymeric films was studied.     

Comment on "Automatic estimation of pressure-dependent rate coefficients" (J. W. Allen, C. F. Goldsmith, and W. H. Green, Phys. Chem. Chem. Phys., 2011, 14, 1131-1155)

In this comment we discuss briefly the relationship between phenomenological rate constants and the solution to the time-dependent multiple-well master equation. Attention is focused on obtaining rate constants using the CSE (chemically significant eigenmode) method. In particular we describe briefly how to obtain rate constants when one or more of the chemically significant eigenvalues merges with the IEREs (internal energy relaxation eigenvalues).     

Comment on "Heat capacity, enthalpy fluctuations, and configurational entropy in broken ergodic systems" [J. Chem. Phys. 133, 164503 (2010)

A critical examination shows that the specific heat and shear modulus relaxation spectra do not support the notions of continuously broken ergodicity and loss of configurational contribution on isothermal glass transition, nor does the long-known result that C(p) → 0 as T → 0 K prove that S(conf) → 0. Spectra show variation of the real and imaginary components due to phase lag and not due to loss of configurational degrees of freedom. The high-frequency shear modulus, G(∞), of glass increases with time as its fictive temperature decreases and dG(∞)∕dT decreases when a glass forms.     

Comment on "The mathematical origins of the kinetic compensation effect" parts 1 and 2 by P. J. Barrie, Phys. Chem. Chem. Phys., 2012, 14, 318 and 327

The concept of kinetic compensation and the associated isokinetic relation continue to be subject to debate, despite the fact that the conditions under which they are to be expected are now well established, and the criteria for deciding that they have been observed are known. We present these conditions and criteria, and the reality of these relations, and stress their importance for catalysis. We then discuss the fact that statistical arguments against their reality continue to be presented. Recently two articles, based upon the statistical point of view have been published in this Journal. We show that, despite the fact that the mathematics of these articles is error free, they present a distorted image of the present understanding of the subject.     

Synthesis,spectroscopy, and catalytic properties of cationic organozirconium adsorbates on "super acidic" sulfated alumina. "Single-site" heterogeneous catalysts with virtually 100 active sites

Sulfated alumina (AlS), a highly Br?nsted acidic sulfated metal oxide, is prepared by the impregnation of gamma-alumina with 1.6 M H(2)SO(4), followed by calcination at 550 degrees C for 3 h. (13)C CPMAS NMR spectroscopy of the chemisorbed (13)C(alpha)-enriched organozirconium hydrocarbyl Cp'(2)Zr((13)CH(3))(2) (2)/AlS (Cp' = eta(5)-(CH(3))(5)C(5)) reveals that the chemisorption process involves M[bond]C sigma-bond protonolysis at the strong surface Br?nsted acid surface sites to yield a "cation-like" highly reactive zirconocenium electrophile, Cp'(2)Zr(13)CH(3)(+). In contrast, chemisorption of 2 on dehydroxylated alumina (DA) yields a similar cation via methide transfer to surface Lewis acid sites, while chemisorption onto dehydroxylated silica yields a mu-oxo Cp'(2)Zr((13)CH(3))-OSi[triple bond] species. Two complementary active site kinetic assays for benzene hydrogenation show that, unlike typical heterogeneous and supported organometallic catalysts, 97 +/- 2% of all Cp'ZrMe(3) (3)/AlS sites are catalytically significant, demonstrating that the species identified by (13)C CPMAS NMR is indeed the active species. 3/AlS mediates benzene hydrogenation with a turnover frequency of 360 h(-1) at 25 degrees C/1.0 atm H(2). Active site assays were also conducted for ethylene polymerization and reveal that 87 +/- 3% of 3/AlS sites are catalytically active, again demonstrating that nearly all zirconium sites are catalytically significant. Relative rates of ethylene homopolymerization mediated by the catalysts prepared via Cp(2)Zr(CH(3))(2) (1), Cp'(2)Zr(CH(3))(2) (2), Cp'Zr(CH(3))(3) (3), Zr(CH(2)TMS)(4) (4), and Zr(CH(2)Ph)(4) (5) (Cp = eta(5)-C(5)H(5)) chemisorption on AlS are 5/AlS > or = 4/AlS > or = 3/AlS > 2/AlS > or = 1/AlS for ethylene homopolymerization at 150 psi C(2)H(4), 60 degrees C. Under identical conditions, the polymerization rate for 3/DA is approximately 1/10th that for 3/AlS.     

Comment on "Multimodal coupling of optical transitions and plasmonic oscillations in rhodamine B modified gold nanoparticles" by M. Stobiecka and M. Hepel, Phys. Chem. Chem. Phys. 2011, 13, 1131

An article recently published in this journal claimed that a resonance enhanced light scattering (RELS) peak for 22 nm gold nanoparticles was observed at 653 nm, which was about 130 nm higher than the surface plasmon resonance maximum. They also claimed to observe RELS from dilute solutions of Rhodamine B, under conditions where it is expected to be in its monomeric form. This comment shows that the position of the RELS peak for the gold nanoparticles is an artefact of measurement and the RELS from Rhodamine B is simply fluorescence. These findings are likely to have a significant impact on the interpretation of the results in terms of interactions of dyes with gold nanoparticles as well as aggregation of gold nanoparticles, which has been reported elsewhere by the same authors.     

Comment on "HCl adsorption on ice at low temperature: a combined X-ray absorption, photoemission and infrared study" by P. Parent, J. Lasne, G. Marcotte and C. Laffon, Phys. Chem. Chem. Phys., 2011, 13, 7142

On the basis of NEXAFS, photoemission and FTIR spectra of ice films with low doses of adsorbed HCl, the authors of the PCCP paper "HCl adsorption on ice at low temperature: a combined X-ray absorption, photoemission and infrared study", Phys. Chem. Chem. Phys., 2011, 13, 7142, have come to conclusions regarding the behavior of submonolayer amounts of HCl at 50 K that contradict published results of the authors of this Comment. Our purpose is to argue that the conclusion, attributed going forward to PLML (authors' initials), that nearly 100% of HCl ionizes for dosage levels near to 0.16 monolayer (ML) or 0.3 Langmuir (L) at 50 K is questionable. Rather, we reaffirm our conclusions of much lower levels of ionization for similar temperatures and HCl dosages based on reactive ion scattering (RIS) and low energy sputtering (LES) data for ice films and FTIR spectra of ice nanocrystals. A second current paper by Ayotte et al., J. Phys. Chem. A, 2011, 115, 6002, that largely parallels in method and results the RAIR spectroscopy of PLML, is also given special notice.