Emergence of practical fluorescence in a confined space of nanoporous silica: significantly enhanced quantum yields of a conjugated molecule

2021 ◽  
Author(s):  
Kosei Hayashi ◽  
Yasuto Fujimaki ◽  
Kentaro Mishiba ◽  
Hiroto Watanabe ◽  
Hiroaki Imai
Keyword(s):  
Carbonyl Group ◽  
Molecular Size ◽  
Quantum Yields ◽  
Nanoporous Silica ◽  
Confined Space ◽  
Conjugated Molecule

The fluorescence of benzanthrone, which is a conjugated molecule bearing a carbonyl group, is activated by confinement in a pore with a diameter close to the molecular size. An intense...

XRD, FTIR and 13C CP/MAS NMR Studies of Composite Comprising Poly(vinyl acetate)-Silylated Si-MCM-41

2011 ◽  
Vol 364 ◽  
pp. 159-163
Author(s):  
Izza Taib Nurul ◽  
Salasiah Endud ◽  
M. Nasir Katun
Keyword(s):  
Carbonyl Group ◽  
Vinyl Acetate ◽  
Silica Matrix ◽  
Mas Nmr ◽  
Polymer Chains ◽  
Confined Space ◽  
Nmr Studies ◽  
Solution Intercalation ◽  
Cp Mas Nmr ◽  
Mcm 41

A composite structure based on silylated MCM-41 and Poly (vinyl acetate) (PVAc) was synthesized via solution intercalation. Poly (vinyl acetate)-silylated Si-MCM-41 composite were characterized by XRD, FTIR spectroscopy and13C CP/MAS NMR in order to determine the compatibility between PVAc and the silicate host. XRD study reveals that the framework of silylated Si-MCM-41 was not altered upon incorporation of PVAc. FTIR study showed that characteristic peak assigned to carbonyl group in PVAc was observed around 1741.6 cm-1for all the composites indicating the presence of PVAc in the silylated Si-MCM-41.13C CP/MAS NMR showed the increase of line width of the peak assigned to C=O carbonyl group indicating the increase in randomness of polymer chains in confined space. The shifting of the C=O carbonyl groups is a sign of the change in chemical environment of the carbonyl owing to the interaction of PVAc with the silica matrix of silylated Si-MCM-41.

scholarly journals Application of Huckel Molecular Orbital Theory (HMO) on Hetero-Conjugated Molecule, 3-Aminopropenal

2001 ◽  
Vol 71 (3) ◽  
pp. 460-465
Author(s):  
Biljana B. Arsic ◽  
Jovica V. Urosevic ◽  
Miroslav M. Mitic
Keyword(s):  
Quantum Mechanics ◽  
Carbonyl Group ◽  
Molecular Orbital ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Conjugation System ◽  
Chemistry Students ◽  
Hückel Molecular Orbital Theory ◽  
Secular Determinant ◽  
Conjugated Molecule

Very often the application of quantum mechanics into chemistry represents a challenging task for chemistry students. However, this can be very usual exercise, and we have shown the easiness on the molecule of 3-aminopropenal, which is an interesting example because of the existence of the conjugation system consisting of the carbonyl group, alkenyl system and the lone electronic pair on nitrogen without any symmetry. Coefficients obtained using the Huckel secular determinant were -2.0484, -1.7328, -0.7827, +0.4892 and +1.5747.

Dipole-Dipole Transport of Excitation in Liquid Solutions: Influence of Multi-Stage Energy Transfer on Donor Photoluminescence Yield

1989 ◽  
Vol 44 (9) ◽  
pp. 821-824 ◽  
Author(s):  
J. Kuśba
Keyword(s):  
Energy Transfer ◽  
Diffusion Coefficients ◽  
Size Effects ◽  
Molecular Size ◽  
Quantum Yields ◽  
Transfer Rates ◽  
Multi Stage ◽  
Donor And Acceptor ◽  
Liquid Solutions ◽  
Dipole Energy

Abstract On the basis of expressions obtained earlier, numerical calculations of relative donor quantum yields in the presence of multi-stage dipole-dipole energy transfer and material diffusion are carried out. Transfer rates of the second order obtained from the numerical solution of the diffusion equation with reflecting boundary conditions are used in the calculations. The results reflect the influence of donor and acceptor concentration, magnitude of diffusion coefficients and molecular size effects.

The Vacuum Ultraviolet Photolysis of Cyclopentanone

1972 ◽  
Vol 50 (24) ◽  
pp. 3938-3943 ◽  
Author(s):  
Alfred A. Scala ◽  
Daniel G. Ballan
Keyword(s):  
Quantum Yield ◽  
Carbonyl Group ◽  
Incident Energy ◽  
Vacuum Ultraviolet ◽  
Quantum Yields ◽  
Electronically Excited ◽  
Ultraviolet Photolysis

In the vacuum ultraviolet photolysis of cyclopentanone, the major modes of fragmentation of the electronically excited ketone are:[Formula: see text]The sum of the quantum yields for reactions A and B is 0.87 at 147.0 nm and these reactions become less important as the incident energy is increased. A pressure study at 147.0 nm of the partitioning of the tetramethylene diradical between paths A and B indicates that the ratio kA/kB is approximately 8. The quantum yield for reaction 8 is only 0.02. The remainder of the decomposition of cyclopentanone is accounted for by reactions 4 and 5, which appear to become more significant as the incident energy increases. The mechanisms for reactions 6 and 8 are best interpreted in terms of diradicals of structure (CH2)n where n = 1, 3, and 4. The lack of non-acyl σ-cleavage at 147.0 nm is an indication that the absorption of energy occurs at the carbonyl group.

scholarly journals Application of spectral graph theory on the enthalpy change of formation of acyclic saturated ketones

2018 ◽  
Vol 83 (12) ◽  
pp. 1339-1349 ◽  
Author(s):  
Ana Gligorijevic ◽  
Svetlana Markovic ◽  
Izudin Redzepovic ◽  
Boris Furtula
Keyword(s):  
Graph Theory ◽  
Carbonyl Group ◽  
Major Part ◽  
Molecular Size ◽  
Enthalpy Change ◽  
Spectral Graph Theory ◽  
Spectral Graph ◽  
Enthalpy Changes ◽  
Calculated Enthalpy ◽  
Acyclic Ketones

The dependence of the enthalpy change of formation of saturated acyclic ketones on molecular structure (the number of carbon atoms, the position of the carbonyl group, and the branching of the molecules) was investigated. For this purpose, a simple computational model, the parameterization of which is based on spectral graph theory, was developed. It was found that the major part of the enthalpy change of formation is determined by molecular size, whereas the fine structure of the enthalpy change of formation is determined by the branching of the molecule and the position of the carbonyl group. The developed model proved itself very useful for such investigations. The model is simple and practical, and the agreement between the experimental and calculated enthalpy changes of formation is very good, with an average relative error of 0.7%.

scholarly journals Red-Shift (2-Hydroxyphenyl)-Benzothiazole Emission by Mimicking the Excited-State Intramolecular Proton Transfer Effect

2021 ◽  
Vol 9 ◽  
Author(s):  
Yong Ren ◽  
Lei Zhou ◽  
Xin Li
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Near Infrared ◽  
Photophysical Properties ◽  
Molecular Size ◽  
Infrared Region ◽  
Intramolecular Proton Transfer ◽  
Quantum Yields ◽  
Organic Fluorophores ◽  
Imaging Probes

Novel strategies to optimize the photophysical properties of organic fluorophores are of great significance to the design of imaging probes to interrogate biology. While the 2-(2-hydroxyphenyl)-benzothiazole (HBT) fluorophore has attracted considerable attention in the field of fluorescence imaging, its short emission in the blue region and low quantum yield restrict its wide application. Herein, by mimicking the excited-state intramolecular proton transfer (ESIPT) effect, we designed a series of 2-(2-hydroxyphenyl)-benzothiazole (HBT) derivatives by complexing the heteroatoms therein with a boron atom to enhance the chance of the tautomerized keto-like resonance form. This strategy significantly red-shifted the emission wavelengths of HBT, greatly enhanced its quantum yields, and caused little effect on molecular size. Typically, compounds 12B and 13B were observed to emit in the near-infrared region, making them among the smallest organic structures with emission above 650 nm.

scholarly journals PRESSOR SUBSTANCES IN ARTERIAL HYPERTENSION

1950 ◽  
Vol 92 (6) ◽  
pp. 561-570 ◽  
Author(s):  
Norman S. Olsen ◽  
Henry A. Schroeder ◽  
Keyword(s):  
Arterial Hypertension ◽  
Carbonyl Group ◽  
Organic Solvents ◽  
Alkaline Solution ◽  
Pressor Response ◽  
Molecular Size ◽  
Amino Group ◽  
Hypertensive Patients ◽  
Arterial Blood

Pherentasin, a material producing a prolonged pressor response in rats, has been procured from the arterial blood of hypertensive patients and purified. Pherentasin is of small molecular size, non-protein in nature, dialyzable, soluble in water and 90 per cent ethanol, and extractable into organic solvents from alkaline solution. It contains an amino group essential to activity, which is probably primary, and also contains an active carbonyl group. It has been found in concentrations up to approximately 20 γ per liter of blood.

Characterization of Recombinant Human Coagulation Factor XFriuli

1996 ◽  
Vol 75 (02) ◽  
pp. 313-317 ◽  
Author(s):  
D J Kim ◽  
A Girolami ◽  
H L James
Keyword(s):  
Catalytic Domain ◽  
Coagulation Factor ◽  
Molecular Size ◽  
Binding Pocket ◽  
Site Directed Mutagenesis ◽  
Bleeding Tendency ◽  
Factor X ◽  
Amino Terminal ◽  
Normal Plasma ◽  
Plasma Factor

SummaryNaturally occurring plasma factor XFriuli (pFXFr) is marginally activated by both the extrinsic and intrinsic coagulation pathways and has impaired catalytic potential. These studies were initiated to obtain confirmation that this molecule is multi-functionally defective due to the substitution of Ser for Pro at position 343 in the catalytic domain. By the Nelson-Long site-directed mutagenesis procedure a construct of cDNA in pRc/CMV was derived for recombinant factor XFriuli (rFXFr) produced in human embryonic (293) kidney cells. The rFXFr was purified and shown to have a molecular size identical to that of normal plasma factor X (pFX) by gel electrophoretic, and amino-terminal sequencing revealed normal processing cleavages. Using recombinant normal plasma factor X (rFXN) as a reference, the post-translational y-carboxy-glutamic acid (Gla) and (β-hydroxy aspartic acid (β-OH-Asp) content of rFXFr was over 85% and close to 100%, respectively, of expected levels. The specific activities of rFXFr in activation and catalytic assays were the same as those of pFXFr. Molecular modeling suggested the involvement of a new H-bond between the side-chains of Ser-343 and Thr-318 as they occur in anti-parallel (3-pleated sheets near the substrate-binding pocket of pFXFr. These results support the conclusion that the observed mutation in pFXFr is responsible for its dysfunctional activation and catalytic potentials, and that it accounts for the moderate bleeding tendency in the homozygous individuals who possess this variant procoagulant.

Suppressive Effect of Dextran on Platelet Adhesiveness

1966 ◽  
Vol 16 (03/04) ◽  
pp. 384-394 ◽  
Author(s):  
S Cronberg ◽  
B Robertson ◽  
Inga Marie Nilsson ◽  
J.-E Niléhn
Keyword(s):  
Molecular Weight ◽  
Bleeding Time ◽  
Slight Modification ◽  
Molecular Size ◽  
Suppressive Effect ◽  
Factor Ix ◽  
Factor V ◽  
Platelet Adhesiveness ◽  
History Of ◽  
Mean Molecular Weight

Summary43 normal volunteers, 3 patients with thrombophlebitis, and 1 patient with a high platelet adhesiveness and a history of thrombophlebitis have received dextran and its action on the mechanism of haemostasis has been studied. Platelet adhesiveness has been investigated by a slight modification of Hellem’s methods for whole blood and plasma. Dextran with a mean molecular weight of 70,000 produced a markedly lowered platelet adhesiveness together with a moderate prolongation of the Ivy bleeding time. Factor VIII was decreased by about 50% and factor V, factor IX and fibrinogen were decreased slightly more than could be expected from haemodilution alone. No fibrinolysis occurred. Dextran of lower molecular size was less potent. The possible use of dextrans as a thrombosis prophylactic agent is discussed.

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