Search results for "Derivative"

Bioavailability and metabolism.

2002

Analytic CCSD(T) second derivatives

1997

A general-purpose implementation of analytic CCSD(T) second derivatives is presented. Its applicability is demonstrated by calculations of vibration-rotation interaction constants for the astrophysically important molecule cyclopropenylidene (C3H2) in which the required cubic force constants have been determined by numerical differentiation of analytically evaluated second derivatives of the energy.

FOUNDATIONS OF FRACTIONAL DYNAMICS

1995

Time flow in dynamical systems is reconsidered in the ultralong time limit. The ultralong time limit is a limit in which a discretized time flow is iterated infinitely often and the discretization time step is infinite. The new limit is used to study induced flows in ergodic theory, in particular for subsets of measure zero. Induced flows on subsets of measure zero require an infinite renormalization of time in the ultralong time limit. It is found that induced flows are given generically by stable convolution semigroups and not by the conventional translation groups. This could give new insight into the origin of macroscopic irreversibility. Moreover, the induced semigroups are generated …

Two in one against motor neuron degeneration: tackling oxidative stress and inflammation with a sulfasalazine derivative.

2012

Electron transfer in a supramolecular associate of a fullerene fragment

2014

Herein, we investigate the association of a fullerene fragment, hemifullerene C30H12, with an electron-donating bowl-shaped tetrathiafulvalene derivative (truxTTF). UV/Vis titrations and DFT calculations support formation of the supramolecular complex, for which an association constant of log Ka = 3.6±0.3 in CHCl3 at room temperature is calculated. Remarkably, electron transfer from truxTTF to C30H12 to form the fully charge-separated species takes place upon irradiation of the associate with light, constituting the first example in which a fullerene fragment mimics the electron-accepting behavior of fullerenes within a supramolecular complex.

Conjugated Porphyrin Dimers: Cooperative Effects and Electronic Communication in Supramolecular Ensembles with C60

2016

International audience; Two new conjugated porphyrin-based systems (dimers 3 and 4) endowed with suitable crown ethers have been synthesized as receptors for a fullerene-ammonium salt derivative (1). Association constants in solution have been determined by UV–vis titration experiments in CH2Cl2 at room temperature. The designed hosts are able to associate up to two fullerene-based guest molecules and present association constants as high as ∼5 × 108 M–1. Calculation of the allosteric cooperative factor α for supramolecular complexes [3·12] and [4·12] showed a negative cooperative effect in both cases. The interactions accounting for the formation of the associates are based, first, on the …

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

2019

We report on nucleus-independent magnetic shielding (NICS) scans over the centers of six- and five-membered rings in selected metal phthalocyanines (MPc) and fullerene C60 for more accurate characterization of local aromaticity in these compounds. Detailed tests were conducted on model aromatic molecules including benzene, pyrrole, indole, isoindole, and carbazole and subsequently applied to H2 Pc, ZnPc, Al(OH)Pc, and CuPc. Similar behavior of three selected magnetic probes, Bq, 3 He, and 7 Li+ , approaching perpendicularly the ring centers, was observed. For better visualization of shielding zone over the centers of aromatic rings, we introduced a simple mathematical procedure: the first a…

Isolation and Characterization of a New Less-Toxic Derivative of the Fusarium Mycotoxin Diacetoxyscirpenol after Thermal Treatment

2011

Trichothecenes are an important class of mycotoxins that act as potent protein synthesis inhibitors in eukaryotic organisms. The compound 4,15-diacetoxyscirpenol is highly toxic for plants and animals. Potatoes are especially prone to be contaminated with 4,15-diacetoxyscirpenol after infection with Fusarium sambucinum. In the current study, the reduction of 4,15-diacetoxyscirpenol during thermal treatment in aqueous solution was monitored. A new derivative was detected and named DAS-M1. After isolation, DAS-M1 was characterized with LC-HR-MS and LC-MS/MS and structurally elucidated with (1)H, (13)C, and 2D NMR. Potatoes were inoculated with F. sambucinum, and the infected potatoes were coo…

Fusaristatins D–F and (7S,8R)-(−)-chlamydospordiol from Fusarium sp. BZCB-CA, an endophyte of Bothriospermum chinense

2021

Abstract Three new lipodepsipeptides, fusaristatins D–F (1–3) and a new α-pyrone derivative, (7S,8R)-(−)-chlamydospordiol (5), together with eight known compounds (4, 6–12) were obtained from solid rice cultures of Fusarium sp. BZCB-CA, an endophyte of the Chinese medicinal plant, Bothriospermum chinense. The planar structures of the new metabolites (1–3, 5) were established by spectroscopic techniques (1D/2D NMR and HRESIMS). Marfey’s method was applied to determine the absolute configuration of 1, while the absolute configuration of 5 was determined by single-crystal X-ray crystallography analysis in addition to Mosher’s method. Crystallographic data of inflatin C (7) are also supplied he…

Simulation of the dynamics of hard ellipsoids

2008

We study a system of uniaxial hard ellipsoids by molecular dynamics simulations, changing both the aspect-ratio X-0 (X-0 = a/b, where a is the length of the revolution axis and b is the length of the two other axes) and the packing fraction phi. We calculate the translational and rotational mean squared displacements, the translational D-trans and the rotational D-rot diffusion coefficients and the associated isodiffusivity lines in the phi - X-0 plane. For the first time, we characterize the cage effect through the logarithmic time derivative of log and log . These quantities exhibit a minimum if the system is supercooled and we show that, consistently with our previous findings, for large…