Steric crowding of a series of pyridine based ligands influencing the photophysical properties of Zn(II) complexes

CrystEngComm ◽  
2021 ◽  
Author(s):  
Daniel Ejarque ◽  
Teresa Calvet ◽  
Mercè Font-Bardia ◽  
Josefina Pons
Keyword(s):  
Photophysical Properties ◽  
Quantum Yields ◽  
Metal Centers ◽  
Steric Crowding

The combination of α-acetamidocinnamic acid (HACA) and different N, N,N and N,N,N pyridines (dPy) leads to crowded Zn(ii) metal centers. The increasing bulkiness competes with the chelation enhanced effect (CHEF) in the resulting quantum yields.

Regioselective Oxidative Cross-Coupling Reaction: Synthesis of Imidazo[1,2-a]pyridine Fluorophores

Synthesis ◽  
2021 ◽  
Author(s):  
Xianglong Chu ◽  
Yadi Niu ◽  
Chen Ma ◽  
Xiaodong Wang ◽  
Yunliang Lin ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Cross Coupling Reaction ◽  
Color Tunable ◽  
Palladium Catalyzed ◽  
Structure Relationship ◽  
High Fluorescence

AbstractA rapid access to a series of N-heteroarene fluorophores has been developed on the basis of the palladium-catalyzed direct oxidative C–H/C–H coupling of imidazo[1,2-a]pyridines with thiophenes/furans. The photophysical properties–structure relationship was systematically investigated. The resulting N-heteroarene fluorophores present color-tunable emissions (λem: 431–507 nm in CH2Cl2) and high fluorescence quantum yields (up to 91% in CH2Cl2).

scholarly journals The Photostability of Novel Boron Hydride Blue Emitters in Solution and Polystyrene Matrix

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 589
Author(s):  
Jakub Ševčík ◽  
Pavel Urbánek ◽  
Barbora Hanulíková ◽  
Tereza Čapková ◽  
Michal Urbánek ◽  
...  
Keyword(s):  
Thin Films ◽  
Photophysical Properties ◽  
Inorganic Compounds ◽  
Solid Polymer ◽  
Organic Polymer ◽  
Quantum Yields ◽  
Boron Hydride ◽  
Polystyrene Matrix ◽  
Blue Emitters ◽  
Solvent Blends

In recent work, the boron hydride anti-B18H22 was announced in the literature as a new laser dye, and, along with several of its derivatives, its solutions are capable of delivering blue luminescence with quantum yields of unity. However, as a dopant in solid polymer films, its luminescent efficiencies reduce dramatically. Clarification of underlying detrimental effects is crucial for any application and, thus, this contribution makes the initial steps in the use of these inorganic compounds in electrooptical devices based on organic polymer thin films. The photoluminescence behavior of the highly luminescent boron hydrides, anti-B18H22 and 3,3′,4,4′-Et4-anti-B18H18, were therefore investigated. The quantum yields of luminescence and photostabilities of both compounds were studied in different solvents and as polymer-solvent blends. The photophysical properties of both boranes are evaluated and discussed in terms of their solvent-solute interactions using photoluminescence (PL) and NMR spectroscopies. The UV degradability of prepared thin films was studied by fluorimetric measurement. The effect of the surrounding atmosphere, dopant concentration and the molecular structure were assessed.

scholarly journals Photochemical Reactivity of Naphthol-Naphthalimide Conjugates and Their Biological Activity

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3355
Author(s):  
Matija Sambol ◽  
Patricia Benčić ◽  
Antonija Erben ◽  
Marija Matković ◽  
Branka Mihaljević ◽  
...  
Keyword(s):  
Biological Activity ◽  
Rational Design ◽  
Human Cancer ◽  
Photophysical Properties ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Quinone Methide ◽  
Quantum Yields ◽  
Photochemical Reactivity ◽  
Human Cancer Cell Lines

Quinone methide precursors 1a–e, with different alkyl linkers between the naphthol and the naphthalimide chromophore, were synthesized. Their photophysical properties and photochemical reactivity were investigated and connected with biological activity. Upon excitation of the naphthol, Förster resonance energy transfer (FRET) to the naphthalimide takes place and the quantum yields of fluorescence are low (ΦF ≈ 10−2). Due to FRET, photodehydration of naphthols to QMs takes place inefficiently (ΦR ≈ 10−5). However, the formation of QMs can also be initiated upon excitation of naphthalimide, the lower energy chromophore, in a process that involves photoinduced electron transfer (PET) from the naphthol to the naphthalimide. Fluorescence titrations revealed that 1a and 1e form complexes with ct-DNA with moderate association constants Ka ≈ 105–106 M−1, as well as with bovine serum albumin (BSA) Ka ≈ 105 M−1 (1:1 complex). The irradiation of the complex 1e@BSA resulted in the alkylation of the protein, probably via QM. The antiproliferative activity of 1a–e against two human cancer cell lines (H460 and MCF 7) was investigated with the cells kept in the dark or irradiated at 350 nm, whereupon cytotoxicity increased, particularly for 1e (>100 times). Although the enhancement of this activity upon UV irradiation has no imminent therapeutic application, the results presented have importance in the rational design of new generations of anticancer phototherapeutics that absorb visible light.

scholarly journals Indenopyrans – synthesis and photoluminescence properties

2016 ◽  
Vol 12 ◽  
pp. 825-834 ◽  
Author(s):  
Andreea Petronela Diac ◽  
Ana-Maria Ţepeş ◽  
Albert Soran ◽  
Ion Grosu ◽  
Anamaria Terec ◽  
...  
Keyword(s):  
Solid State ◽  
Emission Band ◽  
Fluorescence Spectra ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
Band Broadening ◽  
Photoluminescence Properties ◽  
Fluorescence Quantum Yields ◽  
Blue Emitters ◽  
Solid State Fluorescence

New indeno[1,2-c]pyran-3-ones bearing different substituents at the pyran moiety were synthesized and their photophysical properties were investigated. In solution all compounds were found to be blue emitters and the trans isomers exhibited significantly higher fluorescence quantum yields (relative to 9,10-diphenylanthracene) as compared to the corresponding cis isomers. The solid-state fluorescence spectra revealed an important red shift of λmax due to intermolecular interactions in the lattice, along with an emission-band broadening, as compared to the solution fluorescence spectra.

scholarly journals Synthesis, Characterization and Photophysical Properties of a New 2,5-Di(aryl)phosphole Derivative and Their Trigonal Copper-Phosphole Complexes

2020 ◽  
Author(s):  
Neskarlys Rios ◽  
Franmerly Fuentes ◽  
Juan Manuel Garcia Garfido ◽  
Yomaira Otero
Keyword(s):  
Field Strength ◽  
Fluorescence Spectroscopy ◽  
Photophysical Properties ◽  
High Yield ◽  
Quantum Yields ◽  
Ligand Field ◽  
Emission Energy ◽  
Esi Ms

<div>A new phosphole derivative 2,5-di(2-quinolyl)-1-phenylphosphole (<b>1</b>) was synthesized by using the Fagan-Nugent method. Phosphole was obtained as an air stable solid in high yield (73%). Additionally, two new copper phosphole complexes [CuX(Phosphole)<sub>2</sub>] (X = Cl (<b>2a</b>), I (<b>2b</b>), Phosphole = <b>1</b>) have been synthesized by reaction of CuX (X = Cl, I) and phosphole derivative (<b>1</b>). All compound were characterized by NMR, ESI-MS, UV–Vis and fluorescence spectroscopy. The photophysical properties of all compounds were analyzed, UV-Vis spectra of the complexes <b>2a-b</b> shown π–π* transitions with shift very similar to the found in the free phosphole due to that their symmetrical structures inhibits efficient ILCT. We have found that the compounds <b>1</b>, <b>2a-b</b> exhibited fluorescence between 460 and 583 nm with quantum yields of Φ<sub>f</sub> = 0.04 – 0.11. The emission energy of <b>2b</b> is higher than <b>2a</b>, suggesting that λ<sub>max</sub> is affected by the ligand-field strength of the halogen ions in the complexes (I<sup>-</sup> < Cl<sup>-</sup> ).</div>

scholarly journals Synthesis, Characterization and Photophysical Properties of a New 2,5-Di(aryl)phosphole Derivative and Their Trigonal Copper-Phosphole Complexes

2020 ◽  
Author(s):  
Neskarlys Rios ◽  
Franmerly Fuentes ◽  
Juan Manuel Garcia Garfido ◽  
Yomaira Otero
Keyword(s):  
Field Strength ◽  
Fluorescence Spectroscopy ◽  
Photophysical Properties ◽  
High Yield ◽  
Quantum Yields ◽  
Ligand Field ◽  
Emission Energy ◽  
Esi Ms

<div>A new phosphole derivative 2,5-di(2-quinolyl)-1-phenylphosphole (<b>1</b>) was synthesized by using the Fagan-Nugent method. Phosphole was obtained as an air stable solid in high yield (73%). Additionally, two new copper phosphole complexes [CuX(Phosphole)<sub>2</sub>] (X = Cl (<b>2a</b>), I (<b>2b</b>), Phosphole = <b>1</b>) have been synthesized by reaction of CuX (X = Cl, I) and phosphole derivative (<b>1</b>). All compound were characterized by NMR, ESI-MS, UV–Vis and fluorescence spectroscopy. The photophysical properties of all compounds were analyzed, UV-Vis spectra of the complexes <b>2a-b</b> shown π–π* transitions with shift very similar to the found in the free phosphole due to that their symmetrical structures inhibits efficient ILCT. We have found that the compounds <b>1</b>, <b>2a-b</b> exhibited fluorescence between 460 and 583 nm with quantum yields of Φ<sub>f</sub> = 0.04 – 0.11. The emission energy of <b>2b</b> is higher than <b>2a</b>, suggesting that λ<sub>max</sub> is affected by the ligand-field strength of the halogen ions in the complexes (I<sup>-</sup> < Cl<sup>-</sup> ).</div>

scholarly journals The Temperature Dependence of Fundamental Photophysical Properties of [Eu(MeOH-d4)9]3+ Solvates and [Eu.DOTA(MeOH-d4)]- Complexes

2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen
Keyword(s):  
Transition Probabilities ◽  
Photophysical Properties ◽  
Transition Probability ◽  
Energy Levels ◽  
Emission Spectra ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Absorption Cross ◽  
Apparent Lack

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>

Tb2(bpdc)3 and Eu2(bpdc)3 Nanoparticles (bpdc: 2,2ʹ-Bipyridine-4,4ʹ- dicarboxylate) and Their Luminescence

2014 ◽  
Vol 69 (2) ◽  
pp. 248-254 ◽  
Author(s):  
Ana Kuzmanoski ◽  
Claus Feldmann
Keyword(s):  
Colloidal Stability ◽  
Aqueous Suspension ◽  
Earth Metal ◽  
Quantum Yields ◽  
X Ray Diffraction ◽  
Antenna Effect ◽  
Metal Centers ◽  
X Ray ◽  
Suspension Particle ◽  
Absolute Quantum

Tb2(bpdc)3 and Eu2(bpdc)3 nanoparticles (bpdc: 2,2ʹ-bipyridine-4,4ʹ-dicarboxylate) have been prepared via straightforward precipitation from aqueous solution. The nanoparticles exhibit mean diameters of 41(5) nm (Tb2(bpdc)3) and 56(4) nm (Eu2(bpdc)3) and show a very good colloidal stability in aqueous suspension. Particle size and chemical composition have been characterized based on electron microscopy, X-ray diffraction, infrared spectroscopy and thermogravimetry. Photoluminescence validates an efficient excitation of Tb3+/Eu3+ via the bpdc ligand as an antenna that leads to intense characteristic green and red emissions. The absolute quantum yields of Tb2(bpdc)3 and Eu2(bpdc)3 have been determined at 28 and 12%, respectively. Although rare-earth metal-based photoluminescence is typically quenched in water due to vibronic loss processes (v(O-H)), here, the antenna effect and the shielding of the metal centers via the bpdc ligand are very efficient, allowing for an intense green and red emission of the Tb2(bpdc)3 and Eu2(bpdc)3 nanoparticles even in aqueous suspension.

New peripherally substituted lutetium mono and bis phthalocyanines: Synthesis and comparative photophysical and photochemical properties

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1542-1550
Author(s):  
Nagihan Kocaağa ◽  
Öznur Dülger Kutlu ◽  
Ali Erdoğmuş
Keyword(s):  
Mass Spectrometry ◽  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
Synthesis And Characterization ◽  
Type Ii ◽  
H Nmr ◽  
Photochemical Properties

In this study, the synthesis and characterization of mono-(phthalocyaninato) lutetium(III) (1-Cl and 1-F) [Lu[Formula: see text](AcO)(Pc)] (Pc [Formula: see text] phthalocyaninato, AcO [Formula: see text] acetate) and bis-(phthalocyaninato) lutetium(III) (2-Cl and 2-Br) [Lu[Formula: see text]Pc[Formula: see text]] bearing halogenated (F, Cl and Br) phenoxy–phenoxy groups are described and verified by IR, [Formula: see text]H-NMR, UV-vis and mass spectrometry. Photochemical and photophysical properties of 1-F, 1-Cl 2-Cl and 2-Br in DMSO are also presented. A comparison between photophysical and photochemical parameters of mono and bis derivatives showed that mono phthalocyanines are better photosensitizers than bis phthalocyanines. Photophysical and photochemical properties of phthalocyanines are very useful for photodynamic therapy applications. Singlet oxygen quantum yields [Formula: see text] give an indication of the potential of the complexes as photosensitizers in photodynamic therapy applications. The chloro, fluoro, bromo-phenoxy–phenoxy substituted mono-(phthalocyaninato) lutetium(III) complexes (1-Cl and 1-F) gave good singlet oxygen quantum yields (from 0.86 to 0.80) in DMSO. Thus, these complexes show potential as Type II photosensitizers for PDT of cancer.

scholarly journals Multicolor Emission and Photophysical Properties of Proton-Responsive Cyclometallated Iridium(III) Complex in Transparent Cation-Exchange Membrane

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 653
Author(s):  
Hajime Kamebuchi ◽  
Yu Fujimura ◽  
Taiho Yoshioka ◽  
Atsushi Okazawa ◽  
Makoto Tadokoro ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Photophysical Properties ◽  
Thermal Relaxation ◽  
Polymer Chains ◽  
Cation Exchange Membrane ◽  
Quantum Yields ◽  
Transparent Film ◽  
Maximum Emission ◽  
Ph Dependent ◽  
Exchange Membrane

A transparent film allowing tunable multicolor emission based on a composite of an organometallic compound and a cation-exchange membrane has been developed, in which the cyclometallated iridium(III) complex [IrIII(4Py-ppy)3] (=tris[2-(2-pyridinyl-κN)-4-(4-pyridinyl)phenyl-κC]iridium) (1) with pH-dependent emission wavelengths has been incorporated into Nafion by cation exchange. Soaking Nafion in the solution of 1 for 24 h and exposed to buffers at pH 2, 4, and 10 resulted in maximum emission wavelengths of 587, 560, and 503 nm, respectively. The photophysical properties of 1@Nafion were also enhanced, as its maximum emission wavelength was more blue-shifted than those of 602, 564, and 503 nm in the solutions. The emission quantum yields (Φ) and lifetimes (τ) of 1@Nafion prepared under an acidic condition were up to Φ = 1.8% and τ = 0.11, 0.92 μs, which are considerably higher than the corresponding solutions of Φ = 0.5% and τ = 0.02, 0.18 μs. This is attributed to the fact that 1 is surrounded by the polymer chains of Nafion and immobilized in a relatively rigid medium, which hinders non-radiative deactivation such as thermal relaxation.

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