Search results for "Molecular motion"
showing 10 items of 17 documents
Comparison between iMSD and 2D-pCF analysis for molecular motion studies on in vivo cells: The case of the epidermal growth factor receptor.
2018
Image correlation analysis has evolved to become a valuable method of analysis of the diffusional motion of molecules in every points of a live cell. Here we compare the iMSD and the 2D-pCF approaches that provide complementary information. The iMSD method provides the law of diffusion and it requires spatial averaging over a small region of the cell. The 2D-pCF does not require spatial averaging and it gives information about obstacles for diffusion at pixel resolution. We show the analysis of the same set of data by the two methods to emphasize that both methods could be needed to have a comprehensive understanding of the molecular diffusional flow in a live cell.
Nanoscale Engineering of Designer Cellulosomes.
2016
Biocatalysts showcase the upper limit obtainable for high-speed molecular processing and transformation. Efforts to engineer functionality in synthetic nanostructured materials are guided by the increasing knowledge of evolving architectures, which enable controlled molecular motion and precise molecular recognition. The cellulosome is a biological nanomachine, which, as a fundamental component of the plant-digestion machinery from bacterial cells, has a key potential role in the successful development of environmentally-friendly processes to produce biofuels and fine chemicals from the breakdown of biomass waste. Here, the progress toward so-called "designer cellulosomes", which provide an…
“Twin” phosphorous atoms of tetraethyl 2-methyl-piperyd-1-ylmethylenebisphosphonates
2007
Recently, bisaminophosphonates found applications as therapeutic agents for curing bone disorders. When trying to relate the structures of substituted piperid-1-ylmethylenebisphosphonic with their biological properties, non-typical findings that in 31P NMR spectra of 2-methyl-piperid-1-ylmethylenebisphosphonic and 2-ethyl-piperid-1-ylmethylenebisphosphonic acids, two separate singlets from each of the phosphonic groups were observed, while their analogues bearing substituent in position 3 exhibit only one signal. Their presence was explained by freezing of the molecular motions by strong hydrogen bonding between NH and P = O atoms. In this work, synthesis as well as spectroscopic and theore…
Strong Emission Enhancement in pH-Responsive 2:2 Cucurbit[8]uril Complexes
2019
Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional con…
Translational and rotational molecular motion in supercooled liquids studied by NMR and forced Rayleigh scattering
1994
It has been shown that translational diffusion coefficients, Dt, in the supercooled van der Waals liquids, orthoterphenyl, phenolphthaleindimethylether, and salol, have a weaker temperature dependence than the shear viscosity, η, at T ≲ 1.2Tg and can be described by Dt ∼ η−χ with χ < 1 whereas Dr ∼ η−1 applies for the mean rotational diffusion coefficients, Dr, down to the glass transition temperature, Tg. This apparent decoupling of translational and rotational motion has been discussed in relation with possible anomalous short time diffusion, spatial heterogeneity, and cooperative molecular motions close to Tg.
Dipolar and Quadrupolar Freezing in(KBr)1−x(KCN)x
1986
Dipolar and quadrupolar susceptibility measurements are reported for the molecular glass system ${(\mathrm{KBr})}_{1\ensuremath{-}x}{(\mathrm{KCN})}_{x}$ covering a wide range of frequencies. The results allow a direct comparison of the dipolar and quadrupolar anomalies and demonstrate unambiguously that the freezing in of the dipolar and quadrupolar degrees of freedom occurs at different temperatures.
Hydrogen-ion driven molecular motions in Cu2+-complexes of a ditopic phenanthrolinophane ligand
2004
One of the first kinetic evaluations of a metal ion interchange between the two coordination sites of a ditopic macrocycle is presented. Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es ; Soriano Soto, Concepción, Concepcion.Soriano@uv.es ; Verdejo Viu, Begoña, Begona.Verdejo@uv.es
Regional Susceptibility in VCD Spectra to Dynamic Molecular Motions
2018
Experimental and theoretical studies of the vibrational circular dichroism (VCD) spectrum of 3-methyl-1-(methyldiphenlsilyl)-1-phenylbutan-1-ol, whose absolute configuration is key to elucidating the Brook rearrangement of tertiary benzylic α-hydroxylsilanes, are presented. It is found that the entire OH-bending region in this spectrum—a region that provides important marker bands—cannot be reproduced at all by standard theoretical approaches even though other regions are well described. Using a novel approach to disentangle contributions to the rotational strength of these bands, internal coordinates are identified that critically influence the appearance of this part of the spectrum. We s…
Nanoscale heterogeneity if glass-forming liquids: experimental advances
1998
Abstract Recent evidence indicates that in supercooled liquids the cooperativity of molecular motion extends over certain temporal and spatial ranges. A key advance is the experimental and theoretical exploration of higher-order correlation functions that can track the molecular coordinates for more than just two points in time or space. Uncontested experimental determinations of the heterogeneity length scale at the glass transition remain a major goal.
Helix Inversion Controlled by Molecular Motors in Multistate Liquid Crystals.
2020
Unravelling the rules of molecular motion is a contemporary challenge that promises to support the development of responsive materials and is likely to enhance the understanding of functional motion. Advances in integrating light‐driven molecular motors in soft matter have led to the design and realization of chiral nematic (cholesteric) liquid crystals that can respond to light with modification of their helical pitch, and also with helix inversion. Under illumination, these chiral liquid crystals convert from one helical geometry to another. Here, a series of light‐driven molecular motors that feature a rich configurational landscape is presented, specifically which involves three stable …