The long and winding road to new porphycenes

2012 ◽  
Vol 16 (05n06) ◽  
pp. 589-602 ◽  
Author(s):  
Igor Czerski ◽  
Arkadiusz Listkowski ◽  
Jan Nawrocki ◽  
Natalia Urbańska ◽  
Hubert Piwoński ◽  
...  
Keyword(s):  
Fluorescence Polarization ◽  
Hydrogen Transfer ◽  
Single Molecules ◽  
Tert Butyl ◽  
Tautomeric Forms ◽  
By Products ◽  
Double Hydrogen

We describe attempts — not always successful — made over the years to improve the efficiency of porphycene synthesis and to produce novel compounds, custom-designed for specific purposes. New porphycenes are reported, some of them obtained rather unexpectedly as by-products of the planned reactions. Structure and energy computations of possible tautomeric forms in porphycenes substituted by one, two, three, and four tert-butyl groups lead to predictions regarding the kinetics and mechanisms of intramolecular double hydrogen transfer. The occurrence of tautomerization in single molecules of tert-butylsubstituted porphycenes is demonstrated by using fluorescence polarization techniques.

Influence of alkyl substituents in corrphycene on geometry, electronic structure, hydrogen bonding, and tautomerization

2016 ◽  
Vol 20 (01n04) ◽  
pp. 367-377 ◽  
Author(s):  
Alexandr Gorski ◽  
Barbara Leśniewska ◽  
Grażyna Orzanowska ◽  
Jacek Waluk
Keyword(s):  
Hydrogen Transfer ◽  
Opposite Effect ◽  
Energy Structure ◽  
Tautomeric Forms ◽  
Alkyl Groups ◽  
Data Rates ◽  
Computational Data ◽  
Derivatives Of ◽  
Subnanosecond Range ◽  
Double Hydrogen

Geometry, electronic and vibrational structure, and relative energies of different tautomeric forms have been calculated for free base corrphycene and its five tetra-, octa-, and dodeca-alkyl-substituted derivatives, of which only one has been synthesized so far. The results demonstrate that the lowest energy structure always corresponds to the transtautomeric form. Comparison with the experimental IR and X-ray data available for 2,3,6,7,11,12,17,18-octaethylcorrphycene shows, in contrast to previous suggestions, that th. transspecies is dominant both in solution and crystalline phase. Based on structural, spectral, and computational data, rates of double hydrogen transfer can be predicted. Tautomerization is expected to occur in a nanosecond or subnanosecond range. The rate should strongly decrease upon substituting parent corrphycene with alkyl groups at the pyrrolic [Formula: see text] positions, whereas the opposite effect is expected for mesosubstitution. Depending on the position of substituent, planar or nonplanar geometries of the corrphycene chromophore are predicted. The nonplanarity leads to a substantial increase of the intensity of the low energy electronic transitions (Q-bands).

scholarly journals Photocatalytic Oxidation of Methyl Tert-Butyl Ether in Presence of Various Phase Compositions of TiO2

Catalysts ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 35
Author(s):  
Marcel Šihor ◽  
Martin Reli ◽  
Michal Vaštyl ◽  
Květoslava Hrádková ◽  
Lenka Matějová ◽  
...  
Keyword(s):  
Phase Composition ◽  
Photocatalytic Oxidation ◽  
Rutile Phase ◽  
Methyl Tert Butyl Ether ◽  
Butyl Ether ◽  
Tio2 Photocatalysts ◽  
Tert Butyl ◽  
Photogenerated Electrons ◽  
Effective Removal ◽  
By Products

MTBE (methyl tert-butyl ether) represents a rising threat to the environment, especially drinking water, and its effective removal (with all by-products) is necessary. Even a very low concentration of MTBE makes the water undrinkable; therefore, an effective treatment has to be developed. This work is focused on MTBE photocatalytic oxidation in presence of various TiO2 photocatalysts with different phase composition prepared by different methods. It was confirmed the phase composition of TiO2 had the most significant influence on the photocatalytic degradation of MTBE. The rutile phase more easily reduces adsorbed oxygen by photogenerated electrons to superoxide radical, supporting separation of charge carriers. The presence and concentrations of by-products have to be taken into account as well. The conversion of total organic carbon (TOC) was used for the comparison, 40% of TOC was removed after 1 h of irradiation in presence of TiO2–ISOP–C/800 photocatalyst composed of anatase and rutile phase.

Calculations of Mode-Specific Tunneling of Double-Hydrogen Transfer in Porphycene Agree with and Illuminate Experiment

2014 ◽  
Vol 5 (15) ◽  
pp. 2723-2727 ◽  
Author(s):  
Zahra Homayoon ◽  
Joel M. Bowman ◽  
Francesco A. Evangelista
Keyword(s):  
Hydrogen Transfer ◽  
Double Hydrogen

Molecular structure of 5,7-di(tert-butyl)-2-(6,8-dimethyl-4-chloroquinoline-2-yl)-3-hydroxytropone with two tautomeric forms

2016 ◽  
Vol 57 (3) ◽  
pp. 622-624 ◽  
Author(s):  
V. V. Tkachev ◽  
Yu. A. Sayapin ◽  
G. V. Shilov ◽  
V. N. Komissarov ◽  
S. M. Aldoshin ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Tert Butyl ◽  
Tautomeric Forms

scholarly journals Dissection of molecular assembly dynamics by tracking orientation and position of single molecules in live cells

2016 ◽  
Author(s):  
Shalin B. Mehta ◽  
Molly McQuilken ◽  
Patrick La Riviere ◽  
Patricia Occhipinti ◽  
Amitabh Verma ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescence Polarization ◽  
Single Molecules ◽  
Living Cells ◽  
Molecular Assembly ◽  
Higher Order ◽  
Actin Network ◽  
Molecular Assemblies ◽  
Position And Orientation ◽  
Orientation Of Molecules

AbstractRegulation of order, such as orientation and conformation, drives the function of most molecular assemblies in living cells, yet remains difficult to measure accurately through space and time. We built an instantaneous fluorescence polarization microscope, which simultaneously images position and orientation of fluorophores in living cells with single-molecule sensitivity and a time resolution of 100ms. We developed image acquisition and analysis methods to track single particles that interact with higher-order assemblies of molecules. We tracked the fluctuations in position and orientation of molecules from the level of an ensemble of fluorophores down to single fluorophores. We tested our system in vitro using fluorescently labeled DNA and F-actin in which the ensemble orientation of polarized fluorescence is known. We then tracked the orientation of sparsely labeled F-actin network at the leading edge of migrating human keratinocytes, revealing the anisotropic distribution of actin filaments relative to the local retrograde flow of the F-actin network. Additionally, we analyzed the position and orientation of septin-GFP molecules incorporated in septin bundles in growing hyphae of a filamentous fungus. Our data indicate that septin-GFP molecules undergo positional fluctuations within, ∼350nm of the binding site and angular fluctuations within ∼30° of the central orientation of the bundle. By reporting position and orientation of molecules while they form dynamic higher-order structures, our approach can provide new insights into how micron-scale ordered assemblies emerge from nanoscale molecules in living cells.Significance StatementIn living cells, the 3D architecture of molecular assemblies such as chromosomes, lipid bilayers, and the cytoskeleton is regulated through the interaction among their component molecules. Monitoring the position and orientation of constituent molecules is important for understanding the mechanisms that govern the structure and function of these assemblies. We have developed an instantaneous fluorescence polarization microscope to track the position and orientation of fluorescently labeled particles, including single molecules, which form micron-scale macromolecular assemblies in living cells. Our imaging approach is broadly applicable to the study of dynamic molecular interactions that underpin the function of micron-scale assemblies in living cells.

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