Conformational Changes ofmeso-Aryl Substituted Expanded Porphyrins upon Protonation: Effects on Photophysical Properties and Aromaticity

2009 ◽  
Vol 113 (17) ◽  
pp. 5794-5802 ◽  
Author(s):  
Jae-Yoon Shin ◽  
Jong Min Lim ◽  
Zin Seok Yoon ◽  
Kil Suk Kim ◽  
Min-Chul Yoon ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Photophysical Properties ◽  
Expanded Porphyrins

scholarly journals Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4230
Author(s):  
Andreas Windischbacher ◽  
Luca Steiner ◽  
Ritesh Haldar ◽  
Christof Wöll ◽  
Egbert Zojer ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Photophysical Properties ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Red Shift ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Exciton Coupling ◽  
Metal Organic ◽  
Crystalline Metal

In recent years, the photophysical properties of crystalline metal-organic frameworks (MOFs) have become increasingly relevant for their potential application in light-emitting devices, photovoltaics, nonlinear optics and sensing. The availability of high-quality experimental data for such systems makes them ideally suited for a validation of quantum mechanical simulations, aiming at an in-depth atomistic understanding of photophysical phenomena. Here we present a computational DFT study of the absorption and emission characteristics of a Zn-based surface-anchored metal-organic framework (Zn-SURMOF-2) containing anthracenedibenzoic acid (ADB) as linker. Combining band-structure and cluster-based simulations on ADB chromophores in various conformations and aggregation states, we are able to provide a detailed explanation of the experimentally observed photophysical properties of Zn-ADB SURMOF-2: The unexpected (weak) red-shift of the absorption maxima upon incorporating ADB chromophores into SURMOF-2 can be explained by a combination of excitonic coupling effects with conformational changes of the chromophores already in their ground state. As far as the unusually large red-shift of the emission of Zn-ADB SURMOF-2 is concerned, based on our simulations, we attribute it to a modification of the exciton coupling compared to conventional H-aggregates, which results from a relative slip of the centers of neighboring chromophores upon incorporation in Zn-ADB SURMOF-2.

Photophysical Properties of Core-Modified Expanded Porphyrins: Nature of Aromaticity and Enhancement of Ring Planarity

2008 ◽  
Vol 112 (23) ◽  
pp. 6900-6905 ◽  
Author(s):  
Min-Chul Yoon ◽  
Rajneesh Misra ◽  
Zin Seok Yoon ◽  
Kil Suk Kim ◽  
Jong Min Lim ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Expanded Porphyrins

Aromaticity and photophysical properties of various topology-controlled expanded porphyrins

2010 ◽  
Vol 39 (8) ◽  
pp. 2751 ◽  
Author(s):  
Jae-Yoon Shin ◽  
Kil Suk Kim ◽  
Min-Chul Yoon ◽  
Jong Min Lim ◽  
Zin Seok Yoon ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Expanded Porphyrins

Hybrid systems based on organic dyes and clay minerals: Fundamentals and potential applications

Clay Minerals ◽  
2015 ◽  
Vol 50 (5) ◽  
pp. 549-571 ◽  
Author(s):  
Juraj Bujdák
Keyword(s):  
Hybrid Systems ◽  
Clay Minerals ◽  
Hybrid Materials ◽  
Conformational Changes ◽  
Materials Science ◽  
Organic Dyes ◽  
Photophysical Properties ◽  
Resonance Energy Transfer ◽  
Colour Change ◽  
Resonance Energy

AbstractThis review summarizes several aspects of the interactions between organic dyes and clay minerals, and presents some interesting properties of hybrid materials based on these components. It explains the basic phenomena and photophysical properties of dye/clay mineral hybrid systems (DCHS) while examining the role of clay minerals in them. A brief history of using dyes as tools for clay research and on traditional materials based on DCHS is presented. Metachromasy, the phenomenon of colour change related to the formation of dye molecular aggregates is described in detail and analysed from various perspectives. The properties of DCHS, including photoactivity, luminescence, photocatalytic properties, optical anisotropy and non-linear optical properties are analysed in detail. Clay minerals often play a significant role in the occurrence of specific photophysical phenomena such as resonance energy transfer and luminescence quenching and may influence various reactions, such as conformational changes in dye molecules, photochromism, photoisomerization, photosensitization and other photochemical processes. Routes to synthesize various types of hybrid materials are also described here. The relevance of DCHS for clay research, chemistry and materials science is summarized briefly.

Fluorescent ribonucleoside analogues as probes for investigating RNA structure and function

2010 ◽  
Vol 83 (1) ◽  
pp. 213-232 ◽  
Author(s):  
Seergazhi G. Srivatsan ◽  
Anupam A. Sawant
Keyword(s):  
Nucleic Acid ◽  
Conformational Changes ◽  
Rna Structure ◽  
Photophysical Properties ◽  
Local Environment ◽  
Spectroscopic Techniques ◽  
Rna Structures ◽  
Base Pairs ◽  
Target Nucleic Acid ◽  
And Function

Numerous biophysical tools based on fluorescence have been developed to advance the understanding of RNA–nucleic acid, RNA–protein, and RNA–small molecule inter-actions. In this regard, fluorescent ribonucleoside analogues that are sensitive to their local environment provide sensitive probes for investigating RNA structure, dynamics, and recognition. Most of these analogues closely resemble the native ribonucleosides with respect to their overall dimension and have the ability to form canonical Watson–Crick (WC) base pairs. Therefore, it is possible to place these probes near the point of interaction in a target nucleic acid with minimum structural perturbations and gain insight into the intricacies of conformational changes taking place in and around the interaction site. Here, we provide a concise background on the development and recent advances in the applications of base-modified fluorescent ribonucleoside analogue probes. We first present various base-modified fluorescent ribonucleoside analogues, their photophysical properties, and methods to incorporate these analogues into oligoribonucleotides. We then discuss the established spectroscopic techniques, which make use of the fluorescence properties of these emissive ribonucleoside analogues. Finally, we present the applications of base-modified fluorescent ribonucleoside analogues used as probes incorporated into oligoribonucleotides in investigating RNA structures and functions.

ChemInform Abstract: Aromaticity and Photophysical Properties of Various Topology-Controlled Expanded Porphyrins

ChemInform ◽  
2010 ◽  
Vol 41 (43) ◽  
pp. no-no
Author(s):  
Jae-Yoon Shin ◽  
Kil Suk Kim ◽  
Min-Chul Yoon ◽  
Jong Min Lim ◽  
Zin Seok Yoon ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Expanded Porphyrins

scholarly journals Computational Studies of Aromatic and Photophysical Properties of Expanded Porphyrins

2018 ◽  
Vol 122 (20) ◽  
pp. 4756-4767 ◽  
Author(s):  
Rashid R. Valiev ◽  
Isaac Benkyi ◽  
Yuri V. Konyshev ◽  
Heike Fliegl ◽  
Dage Sundholm
Keyword(s):  
Photophysical Properties ◽  
Computational Studies ◽  
Expanded Porphyrins

scholarly journals BODIPY Dyes as Probes and Sensors to Study Amyloid-β-Related Processes

Biosensors ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 192
Author(s):  
Sergei V. Dzyuba
Keyword(s):  
Small Molecule ◽  
Conformational Changes ◽  
Self Assembly ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Amyloid Β ◽  
Amyloid Formation ◽  
Diverse Range ◽  
Aβ Peptides ◽  
Underlying Mechanisms

Amyloid formation plays a major role in a number of neurodegenerative diseases, including Alzheimer’s disease. Amyloid-β peptides (Aβ) are one of the primary markers associated with this pathology. Aβ aggregates exhibit a diverse range of morphologies with distinct pathological activities. Recognition of the Aβ aggregates by using small molecule-based probes and sensors should not only enhance understanding of the underlying mechanisms of amyloid formation, but also facilitate the development of therapeutic strategies to interfere with amyloid neurotoxicity. BODIPY (boron dipyrrin) dyes are among the most versatile small molecule fluorophores. BODIPY scaffolds could be functionalized to tune their photophysical properties to the desired ranges as well as to adapt these dyes to various types of conditions and environments. Thus, BODIPY dyes could be viewed as unique platforms for the design of probes and sensors that are capable of detecting and tracking structural changes of various Aβ aggregates. This review summarizes currently available examples of BODIPY dyes that have been used to investigate conformational changes of Aβ peptides, self-assembly processes of Aβ, as well as Aβ interactions with various molecules.

Covalently Linked Tetraphenylporphyrin Trimers and Tetramers and their Coordination Behaviour

1997 ◽  
Vol 01 (01) ◽  
pp. 17-28 ◽  
Author(s):  
G. VAIJAYANTHIMALA ◽  
V. KRISHNAN
Keyword(s):  
Energy Transfer ◽  
Conformational Changes ◽  
Photophysical Properties ◽  
Molecular Mechanics Calculations ◽  
Efficient Energy Transfer ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
H Nmr ◽  
Coordination Behaviour ◽  
Covalently Linked

Several covalently linked tetraphenyl porphyrin trimers and tetramers bearing ethylene oxide bridges originating from the m and p positions of adjacent and/or opposite meso-aryl groups have been synthesized and characterized by fast atom bombardment mass spectroscopy, 1 H NMR, optical absorption and emission spectroscopies. The fully and partially metallated zinc(II) and copper(II) derivatives have been prepared and their photophysical properties are outlined. The steady-state and time-resolved fluorescence studies of the heterotrimers indicate efficient energy transfer from the ZnP to the H 2 P unit. The efficiency and rate of energy transfer are dependent on the number of free-base units in the hetero-oligomers and the geometrical position of the porphyrin units. The heterotrimers consisting of one, two and three zinc(II) centres bind 4,4″-bipyridyl in different modes as revealed by the nature of binding curves. The bipyridyl ligand functions as a chelate in the complexes of biszinc(II) porphyrin trimers while two bipyridyls bind to trizinc(II) porphyrin trimers with one ligand functioning as a chelate and another exhibiting monodentate coordination behaviour. The folding of two ZnP units is clearly seen in the complexes of bis and triszinc(II) trimers with bipyridyl, which is substantiated by molecular mechanics calculations. Axial ligation studies with trimers show that the preorganization of porphyrin hosts is necessary for recognition of the guest. The binding of bipyridyl to the trimers is followed by global conformational changes and this behaviour is analogous to activated complex binding in induced-fit enzymes.

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