[10]CPP-Based Inclusion Complexes of Charged Fulleropyrrolidines. Effect of the Charge Location on the Photoinduced Electron Transfer

A number of non-covalently bound donor-acceptor dyads, consisting of C₆₀ as the electron acceptor and cycloparaphenylene (CPP) as the electron donor, have been reported. A hypsochromic shift of the charge transfer (CT) band in polar medium has been found in [10]CPP⊃Li⁺@C₆₀ . To explore this anomalous effect, we study inclusion complexes [10]CPP⊃Li⁺@C₆₀-MP , [10]CPP⊃C₆₀-MPH⁺ , and [10]CPP⊃C₆₀-PPyMe⁺ formed by fulleropyrrolidine derivatives and [10]CPP using the DFT/TDDFT approach. We show that the introduction of a positively charged fragment into fullerene stabilizes CT states that become the lowest-lying excited states. These charge-separated states can be generated by the decay of locally excited states on a nanosecond to picosecond time scale. The distance of the charged fragment to the center of the fullerenic cage and its accessibility to the solvent determine the strength of the hypsochromic shift.     

Best Approximations and Kolmogorov and Trigonometric Widths of the Classes <Emphasis Type="Italic">B</Emphasis><Stack><Subscript><Emphasis Type="Italic">p</Emphasis>,θ</Subscript><Superscript>Ω</Superscript></Stack> of Periodic Functions of Many Variables

We obtain estimates exact in order for the best approximations and Kolmogorov and trigonometric widths of the classes B _p,θ ^Ω of periodic functions of many variables in the space L ^q for certain values of the parameters p and q.__________Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 56, No. 11, pp. 1557–1568, November, 2004.     

Use of differentiation and smoothing in linear-sweep and staircase stripping voltammetry of some metals

Two methods of signal smoothing were considered: square-wave (moving average) and triangular (weighted average) filters. It was found that smoothing by these two filters did not distort noticeably the signal shape and the linearity of calibration plots. Calibration plots for several series of analytical signals of heavy metals were studied. Analytical signals were obtained by stripping voltammetry using a mercury thin-film electrode and processed using the peak area, the peak height, and the range of the extrema of the first and second peak derivatives. It was shown that, for staircase stripping voltammetry, the linearity of calibration plots decreases substantially in this series of signal processing methods. For linear sweep, calibration plots were linear over the entire concentration range for all signal-processing methods. Presented at the V All-Russian Conference with the Participation of CIS Countries on Electrochemical Methods of Analysis (EM A-99), Moscow, December 6–8, 1999.     

Best m-ter m approxi mation of the classes$$ B_{\infty, \theta }^r $$ of functions of many variables by polyno mials in the haar syste m

We obtain an exact-order estimate for the best m-term approximation of the classes B_{￥, q}^r B_{\infty, \theta }^r of periodic functions of many variables by polynomials in the Haar system in the metric of the space L _q , 1 < q < ∞.     

All‐Fullerene Electron Donor–Acceptor Conjugates

The synthesis and characterization of a covalent all‐fullerene C₆₀‐Lu₃N@I_h‐C₈₀ electron donor–acceptor conjugate has been realized by sequential 1,3‐dipolar cycloaddition reactions of azomethine ylides on Lu₃N@I_h‐C₈₀ and C₆₀. To the best of our knowledge, this is the first time that two fullerenes behaving as both electron donor (Lu₃N@I_h‐C₈₀) and acceptor (C₆₀) are forming an electroactive dumbbell. DFT calculations reveal up to 16 diastereomeric pairs, that is, 8 with syn and 8 with anti orientation, with the anti‐RSSS isomer being the most stable. Spectroelectrochemical absorption and femtosecond transient absorption experiments support the notion that a C₆₀^??‐Lu₃N@I_h‐C₈₀^?+ charge‐separated state is formed. Spin conversion from the charge‐separated singlet state C₆₀^??‐Lu₃N@I_h‐C₈₀^?+ into the corresponding triplet state is facilitated by the heavy‐atom effect stemming from the Lu₃N‐cluster, which, in turn, slows down the charge recombination by one order of magnitude.     

Numerical solution of three-dimensional static problems of elasticity for a body with a noncanonical inclusion

A boundary-element scheme is proposed for the numerical determination of the stress-strain state of a three-dimensional composite body, which is an elastic inclusion of arbitrary shape perfectly bonded to an infinite elastic matrix. The scheme involves the reduction of the original problem to six boundary integral equations for the components of interfacial displacements and forces and the boundary-element parametrization and discretization of these equations using generalized Gaussian integrals and topological maps with regularizing Jacobians. Numerical results are obtained for a cylindrical inclusion with rounded ends in a matrix subject at infinity to constant forces acting along this fiber. The influence of the length-to-radius ratio of the fiber and the ratio of the elastic moduli of the matrix and fiber on the stresses is examined __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 4, pp. 27–35, April 2007.