A pyrene-based optical probe capable of molecular computation using chemical input strings

RSC Advances ◽  
2015 ◽  
Vol 5 (64) ◽  
pp. 51678-51681 ◽  
Author(s):  
Megha Chhatwal ◽  
Anup Kumar ◽  
Rinkoo D. Gupta ◽  
Satish K. Awasthi
Keyword(s):  
Optical Probe ◽  
Molecular Computing ◽  
Quantum Yields ◽  
Molecular Computation ◽  
Input Strings

Elucidation of molecular computing by employing a pyrene-based chemosensor with Cu2+, Fe3+, CN− and H+ ions as input stimuli and subsequent quantum yields as output responses.

Highly Luminescent 4-Pyridyl-Extended Dithieno[3,2-b:2′,3′-d]phospholes

2020 ◽  
Author(s):  
Thomas Baumgartner ◽  
Paul Demay-Drouhard
Keyword(s):  
Electrochemical Properties ◽  
Quantum Yields

The unexpectedly challenging synthesis of 4-pyridyl-extended dithienophospholes is reported. The optical and electrochemical properties of the phosphoryl-bridged species were studied experimentally and computationally, and their properties compared to their non-<i>P</i>-bridged congeners. The 4-pyridyl-extended dithieno-phospholes display quantitative luminescence quantum yields in solution.<br><br>

Highly Luminescent 4-Pyridyl-Extended Dithieno[3,2-b:2′,3′-d]phospholes

2020 ◽  
Author(s):  
Thomas Baumgartner ◽  
Paul Demay-Drouhard
Keyword(s):  
Electrochemical Properties ◽  
Quantum Yields

The unexpectedly challenging synthesis of 4-pyridyl-extended dithienophospholes is reported. The optical and electrochemical properties of the phosphoryl-bridged species were studied experimentally and computationally, and their properties compared to their non-<i>P</i>-bridged congeners. The 4-pyridyl-extended dithieno-phospholes display quantitative luminescence quantum yields in solution.<br><br>

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

Symmetry Breaking and the Turn-On Fluorescence of Small, Highly Strained Carbon Nanohoops

2019 ◽  
Author(s):  
Terri Lovell ◽  
Curtis Colwell ◽  
Lev N. Zakharov ◽  
Ramesh Jasti
Keyword(s):  
Symmetry Breaking ◽  
Theoretical Work ◽  
P Systems ◽  
Quantum Yields ◽  
Size Dependent ◽  
New Class ◽  
Carbon Carbon Bond ◽  
Conjugated Macrocycles ◽  
Structural Manipulation ◽  
Highly Strained

<p>[<i>n</i>]Cycloparaphenylenes, or “carbon nanohoops,” are unique conjugated macrocycles with radially oriented p-systems similar to those in carbon nanotubes. The centrosymmetric nature and conformational rigidity of these molecules lead to unusual size-dependent photophysical characteristics. To investigate these effects further and expand the family of possible structures, a new class of related carbon nanohoops with broken symmetry is disclosed. In these structures, referred to as <i>meta</i>[<i>n</i>]cycloparaphenylenes, a single carbon-carbon bond is shifted by one position in order to break the centrosymmetric nature of the parent [<i>n</i>]cycloparaphenylenes. Advantageously, the symmetry breaking leads to bright emission in the smaller nanohoops, which are typically non-fluorescent due to optical selection rules. Moreover, this simple structural manipulation retains one of the most unique features of the nanohoop structures-size dependent emissive properties with relatively large extinction coefficents and quantum yields. Inspired by earlier theoretical work by Tretiak and co-workers, this joint synthetic, photophysical, and theoretical study provides further design principles to manipulate the optical properties of this growing class of molecules with radially oriented p-systems.</p>

Symmetry Breaking and the Turn-On Fluorescence of Small, Highly Strained Carbon Nanohoops

2019 ◽  
Author(s):  
Terri Lovell ◽  
Curtis Colwell ◽  
Lev N. Zakharov ◽  
Ramesh Jasti
Keyword(s):  
Symmetry Breaking ◽  
Theoretical Work ◽  
P Systems ◽  
Quantum Yields ◽  
Size Dependent ◽  
New Class ◽  
Carbon Carbon Bond ◽  
Conjugated Macrocycles ◽  
Structural Manipulation ◽  
Highly Strained

<p>[<i>n</i>]Cycloparaphenylenes, or “carbon nanohoops,” are unique conjugated macrocycles with radially oriented p-systems similar to those in carbon nanotubes. The centrosymmetric nature and conformational rigidity of these molecules lead to unusual size-dependent photophysical characteristics. To investigate these effects further and expand the family of possible structures, a new class of related carbon nanohoops with broken symmetry is disclosed. In these structures, referred to as <i>meta</i>[<i>n</i>]cycloparaphenylenes, a single carbon-carbon bond is shifted by one position in order to break the centrosymmetric nature of the parent [<i>n</i>]cycloparaphenylenes. Advantageously, the symmetry breaking leads to bright emission in the smaller nanohoops, which are typically non-fluorescent due to optical selection rules. Moreover, this simple structural manipulation retains one of the most unique features of the nanohoop structures-size dependent emissive properties with relatively large extinction coefficents and quantum yields. Inspired by earlier theoretical work by Tretiak and co-workers, this joint synthetic, photophysical, and theoretical study provides further design principles to manipulate the optical properties of this growing class of molecules with radially oriented p-systems.</p>

Synthesis and Biological Evaluations of Organoruthenium Scaffolds: A Comprehensive Update

2018 ◽  
Vol 15 (2) ◽  
pp. 179-207
Author(s):  
Ashaparna Mondal ◽  
Priyankar Paira
Keyword(s):  
Singlet Oxygen ◽  
Anticancer Agents ◽  
Ruthenium Complexes ◽  
Chemotherapeutic Agents ◽  
Quantum Yields ◽  
Ros Generation ◽  
Standard Drug ◽  
Cellular Environment ◽  
Theranostic Agents

Background: Currently ruthenium complexes are immerging as effective anticancer agents due to their less toxicity, better antiproliferative and antimetastatic activity, better stability in cellular environment and most importantly variable oxidation and co-ordination states of ruthenium allows binding this molecule with a variety of ligands. So in past few years researchers have shifted their interest towards organoruthenium complexes having good fluorescent profile that may be applicable for cancer theranostics. Nowadays, photodynamic therapy has become more acceptable because of its easy and effective approach towards killing cancer cells. Objective: Objective of this review article is to shed light on synthesis, characterization, stability and fluorescence studies of various ruthenium [Ru(II) and Ru(III)] complexes and different bioactivity studies conducted with the synthesized compounds to test their candidacy as potent chemotherapeutic agents. Methods: Various heterocyclic ligands containing N,O and S as heteroatom mainly were prepared and subjected to complexation with ruthenium-p-cymene moiety. In most cases [Ru(η6-p-cymene)(µ-Cl)Cl]2 was used as ruthenium precursor and the reactions were conducted in various alcohol medium such as methanol, ethanol or propanol. The synthesized complexes were characterized by 1H NMR and 13C NMR spectroscopy, GC-MS, ESI-MS, elemental analysis and single crystal X-ray crystallography methods. Fluorescence study and stability study were conducted accordingly using water, PBS buffer or DMSO. Stable compounds were considered for cell viability studies. To study the efficacy of the compounds in ROS generation as photosensitizers, in few cases, singlet oxygen quantum yields in presence of light were calculated. Suitable compounds were selected for in vitro & in vivo antiproliferative, anti-invasive activity studies. Result: Many newly synthesized compounds were found to have less IC50 compared to a standard drug cysplatin. Those compounds were also stable preferably in physiological conditions. Good fluorescence profile and ROS generation ability were observed for few compounds. Conclusion: Numerous ruthenium complexes were developed which can be used as cancer theranostic agents. Few molecules were synthesized as photosensitizers which were supposed to generate reactive singlet oxygen species in targeted cellular environment in presence of a particular type of light and thereby ceasing cancer cell growth.

Spectrocoulometry – a new spectro-electrochemical technique

1987 ◽  
Vol 52 (6) ◽  
pp. 1386-1396 ◽  
Author(s):  
Ján Mocák ◽  
Michal Németh ◽  
Mieczyslaw Lapkowski ◽  
Jerzy W. Strojek
Keyword(s):  
Optical Probe ◽  
Optical Signal ◽  
Open Circuit ◽  
Electrochemical Technique ◽  
Kinetics Of Oxidation ◽  
Hydrolytic Reaction ◽  
Experimental Errors ◽  
Mechanism And Kinetics ◽  
Kinetics Of

A spectrocoulometric macrocell with a direct-view optical probe was designed and constructed, where the optical signal is transferred by light-conducting glass or quartz fibres permitting to work at wavelengths above 410 or 300 nm. The method of measurement on the proposed equipment is described; it was tested in the study of the mechanism and kinetics of oxidation of Fe(bipy)32+ ions (bipy = 2,2'-bipyridyl) with the use of potentiostatic coulometric electrolysis with open-circuit relaxation at a suitable time. The primary product of electrolysis, Fe(bipy)33+, undergoes a follow-up hydrolytic reaction with the formation of a binuclear complex. The rate constant of the reaction of the first order involves the contributions, kBi, from all bases present in solution; the corresponding values for H2O, OH-, bipy, and CH3COO- ions at a ionic strength 0·5 mol dm-3 and 25 °C were determined as kOH = (5·0 ± 0·6) . 105 mol-1 dm3 s-1, kbipy = (1·3 ± 0·2) . 10-1 mol-1 dm3 s-1, kAc = (5·8 ± 1·0) . 10-2 mol-1 dm3 s-1, and kH2O is not significant with respect to experimental errors.

Regioselectivity of nucleophilic aromatic photosubstitution in the biphenyl series. Photohydrolysis of some dimethoxynitrobiphenyls

1987 ◽  
Vol 52 (10) ◽  
pp. 2482-2491 ◽  
Author(s):  
Ján Urban ◽  
Petr Kuzmič ◽  
David Šaman ◽  
Milan Souček
Keyword(s):  
Nitro Group ◽  
Steric Hindrance ◽  
The Other ◽  
Quantum Yields ◽  
Hydroxide Anion ◽  
Tert Butanol ◽  
Nitro Derivatives

Anaerobic photolysis of dimethoxynitrobiphenyls IIIa-VIa in aqueous alkaline tert-butanol gave products of nucleophilic photosubstitution of methoxyl by hydroxide anion, while the dimethoxybiphenyls Ia and IIa were found unreactive. Regioselectivity of the reaction was examined in view of a possible “extended meta activation” by the nitro group. The most reactive substrate IIIa gives both C-3 and C-4 substitution products with an unsubstantial preference for the latter, which opposes the “extended meta selectivity” rule. All of the other compounds obey the rule, and 3,4-dimethoxy-3'-nitrobiphenyl (IVa) even displayed absolute selectivity by yielding C-3 substituted compound as the only product. 2,5-Dimethoxy substituted compounds underwent photosubstitution which much lower quantum yields than their 3,4-substituted counterparts, most probably due to some steric hindrance of conjugation. Similarly, 3-nitro-substituted biphenyls exhibited much lower overall reactivity than 4-nitro derivatives.

Photoinduced rearrangement of hydroxymethylisoxazolines, a route to enaminoaldehydes

1986 ◽  
Vol 51 (10) ◽  
pp. 2167-2180 ◽  
Author(s):  
Lubor Fišera ◽  
Nadezhda D. Kozhina ◽  
Peter Oravec ◽  
Hans-Joachim Timpe ◽  
Ladislav Štibrányi ◽  
...  
Keyword(s):  
Thionyl Chloride ◽  
Quantum Yields ◽  
Acid Catalyzed ◽  
Catalyzed Reactions ◽  
Photoinduced Rearrangement ◽  
Condensed Heterocycles

3-Aryl-4-R-carbamoyl-5-hydroxymethylisoxazolines (IV) were synthesized by allowing R-NH2 amines with R = H, CH3, C3H7, C6H5C2H5, and NH2 to act on 3-(X-phenyl)-4-oxo-3a,4,6,6a-tetrahydrofuro[3,4-d]isoxazoles (III) with X = H, 4-CH3, 4-OCH3, 2-OCH3, 4-Cl, 2-Cl, 4-F, 2-F, 4-Br, 4-NO2, and 3-NO2. Exposed to radiation, the substances IV give Z-2-hydroxymethylamino-2-aryl-1-formylacrylamides (V) in good yields. The 4-Cl and 4-F substituted Z-derivatives V isomerize irreversibly to the E-derivatives VI if allowed to stand in solvent; the remaining derivatives V are stable. The quantum yields of the photoreaction are from 0.012 to 0.106 in dependence on the substituent X. In all cases where the compounds IV were used for the preparation of condensed heterocycles in conditions of acid-catalyzed reactions, lactones III were preferentially formed; the action of thionyl chloride on IV results in the formation of chloromethyl derivatives VIII, which do not undergo further cyclization.

Photooxidation effect of cupric complexes on aliphatic alcohols in nonaqueous solutions

1982 ◽  
Vol 47 (8) ◽  
pp. 2061-2068 ◽  
Author(s):  
Jan Sýkora ◽  
Mária Jakubcová ◽  
Zuzana Cvengrošová
Keyword(s):  
Coordination Sphere ◽  
Alcohol Oxidation ◽  
Aliphatic Alcohols ◽  
Oxidation Products ◽  
Molar Ratio ◽  
Quantum Yields ◽  
Nonaqueous Solutions ◽  
The Absolute ◽  
Absolute Quantum

In the photolysis of copper(II)-chloride-alcohol-acetonitrile systems (cCu = 1 mmol l-1, copper(II)-to-chloride molar ratio 1 : 2 to 1 : 8, 10% (v/v) alcohol), Cu(II) is reduced to Cu(I), and methanol, ethanol, 1-propanol, or 1-butanol is oxidized to the corresponding aldehyde, 2-propanol to acetone. In the case of 1-propanol and 1-butanol, chlorinated aldehydes are formed in addition too. The measured quantum yields of the photoreduction of Cu(II) to Cu(I) lay in the range of ΦCu(I) = 4.5 to 40 mmol einstein-1, the absolute quantum yields of the alcohol oxidation products were 2.3 to 47 mmol einstein-1. The photoactive components are chlorocupric complexes [CuClx](2-x)+ (x = 1-4). The presence of complexes with a higher number of chloroligands in the coordination sphere (x = 3, 4) brings about a decrease in the Cu(II) photoreduction rate. The decrease in the photoreduction rate observed in the presence of dioxygen is explained in terms of re-oxidation of copper(I) by the latter, resulting in an increase in the concentration of the photochemically active cupric complexes. The catalytic aspects of the systems in question are discussed with respect to this effect.

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