Distance-dependent activation energies for hole injection from protonated 9-amino-6-chloro-2-methoxyacridine into duplex DNA

The recent investigation of the apparently anomalous attenuation factor (beta > 1.5 A(-1)) for photoinduced hole injection into DNA duplexes modified by protonated 9-amino-6-chloro-2-methoxyacridine (X+) led to the conclusion that in addition to the electronic couplings, the activation energy must also be distance-dependent. In this communication we report the verification of this postulate by direct measurements of the activation energies for a series of (X+)-modified DNA duplexes which sample an appreciable range of donor-acceptor distances (approximately 4-11 A). The resulting changes in thermal activation energy can be explained within the framework of a distance-dependent reorganization energy.     

An Improved Synthesis and NMR Spectra of Benzylated Glycals

Abstract

Benzylated glycals, unlike their acylated congeners which easily undergo allylic rearrangement, are frequently employed as reactive enol ether type substrates in a variety of electrophilic addition reactions.^1–4 Although these compounds are considered to be readily available substrates, reported procedures for their syntheses involve some steps of limited efficiency, chromatographic separations or costly reagents,^5–7 and experimental requirements not amenable for large scale preparations. In view of the recent applications of benzylated glycals to syntheses of O-glycosides,^1,2 C-glycosyl compounds,³ and β-lactams,⁴ we have undertaken a study aimed at efficient one step benzylation procedures applicable to pyranoid 1-enitols as well as to their acylated derivatives. This goal was eventually achieved by employing a catalytic phase transfer alkylation system with     

Thiol–Yne Click Reactions on Alkynyl–Dopamine‐Modified Reduced Graphene Oxide

The large‐scale preparation of graphene is of great importance due to its potential applications in various fields. We report herein a simple method for the simultaneous exfoliation and reduction of graphene oxide (GO) to reduced GO (rGO) by using alkynyl‐terminated dopamine as the reducing agent. The reaction was performed under mild conditions to yield rGO functionalized with the dopamine derivative. The chemical reactivity of the alkynyl function was demonstrated by post‐functionalization with two thiolated precursors, namely 6‐(ferrocenyl)hexanethiol and 1H,1H,2H,2H‐perfluorodecanethiol. X‐ray photoelectron spectroscopy, UV/Vis spectrophotometry, Raman spectroscopy, conductivity measurements, and cyclic voltammetry were used to characterize the resulting surfaces.     

New spectroscopic investigations of the fourth-positive (AΠ → XΣ) system bands in the CO molecule

The present work puts forward the results of the recordings carried out under high resolution by conventional, photographic spectroscopy and modern analysis of thirteen bands with v′ = 7-12 and v″ = 16-24 of the fourth-positive (A¹Π → X¹Σ⁺) band system. The current investigations include the region of the observed ¹³C¹⁶O molecule spectrum, much greater now than before. Especially, new transitions connected with not hitherto observed v′ = 12 vibrational level of the A¹Π state, were recorded and studied. Moreover, the region of perturbations observed in the upper state of the fourth-positive system was significantly enlarged. The observed perturbations were confronted with those predicted from theoretical calculations.     

Coupled commensurate cation and charge modulation in the tunneled structure, Na(0.40(2))MnO(2)

Na(0.40(2))MnO(2) belongs to a family of mixed Mn(3+) and Mn(4+) porous oxides that contains both octahedral and square pyramidal Mn-O units. Neutron and synchrotron radiation studies identify the presence of both sodium ordering (T(Na) ≈ 310 K) and Mn charge and orbital ordering. Below T(Na), the centrosymmetric Pbam structure adopts an (ab 4c) supercell of Pnnm symmetry that accommodates a coupled commensurate modulation down the c-axis channels of both Na position and occupancy with Mn valence.     

Influence of the finite lifetime of hydrogen jump phase on the quasi-elastic neutron scattering by hydrogen in metals†

A complex jump diffusion model assuming a finite lifetime for hydrogen both in the jump and in the residence phases is developed as a straightforward extension of the known Rowe et al. theory [1], and also of the Multi-Sublattice Jump Diffusion Model [2]. The residence-residence, jump-jump, residence-jump and vice versa transitions of hydrogen are explicitly included in the model. This approach is a method for calculating the double differential, d²σ/dΩdω, and hence the differential, dσ/dΩ, cross section for quasi-elastic neutron scattering from metal hydrides, MeH_x. In terms of the model we have calculated the diffusion coefficient, which reveals explicitly the contributions of the residence and jump phases.