Highly Emissive Lanthanide Compounds in Sol-Gel Derived Materials

1989 ◽  
Vol 155 ◽  
Author(s):  
Ronald B. Lessard ◽  
Kris A. Berglundl ◽  
Daniel G. Nocera
Keyword(s):  
Aqueous Solution ◽  
Excited State ◽  
Excited States ◽  
Sol Gel ◽  
Water Molecules ◽  
Lanthanide Ion ◽  
Silica Glasses ◽  
Quenching Process ◽  
Molecular Composites ◽  
Glassy Matrices

ABSTRACTMolecular composites that possess unique emission properties have been prepared by introducing luminescent molecules into sol-gel based silica glasses. The lumophores chosen for study are terbium(III) and europium(III) ions whose emissions are quenched in aqueous and sol-gel environments owing to coordination of water molecules to the lanthanide ion. To overcome the quenching process the ions have been encapsulated within cryptands. The resulting terbium(IU) and europium(III) cryptates possess long-lived excited states in both aqueous solution and solgel glassy matrices. Measurements of the excited state dynamics of these molecularly engineered composites demonstrate the feasibility of tailoring molecules to retain their excited state properties in sol-gel derived glasses.

Femtosecond fluorescence studies of Auramine O in hybrid sol-gel derived films

2004 ◽  
Vol 847 ◽  
Author(s):  
P. Prosposito ◽  
A. Quatela ◽  
H. Zhang ◽  
M. Glasbeek
Keyword(s):  
Excited State ◽  
Excited States ◽  
Sol Gel ◽  
Stokes Shift ◽  
Fluorescence Studies ◽  
Spectral Shifts ◽  
Fluorescence Upconversion ◽  
Liquid Solutions ◽  
Phenyl Rings ◽  
Auramine O

ABSTRACTFemtosecond fluorescence upconversion experiments have been performed on Auramine O (a diphenylmethane dye) in polymethylmethacrylate (PMMA) and in hybrid organic/inorganic solgel based films.All the investigated samples showed a fast decay (few picoseconds) and a long decay (hundreds of picoseconds). The fast components are representative of the rapid cooling of the excess excitation energy to the matrices. The long components are representative of the excited-state lifetime of the probed molecules. Auramine O in solid matrices showed lifetimes longer than in liquid solutions. Torsional diffusion motions of the two phenyl rings of the molecule are held responsible for the excited-state dynamics.A dynamic Stokes shift has been observed for all samples. The lack of a rise time when detection was on the red side is explained in terms of an adiabatic coupling between emissive and nonemissive excited states, as is the case of liquid solutions. Different spectral shifts in PMMA and hybrid glasses have been measured. A different coupling between the emissive and nonemissive excited states for the two types of matrices is considered.

Light Harvesting Molecular Assemblies in the Design of Highly Luminescent Sol-Gel Derived Glasses

1990 ◽  
Vol 180 ◽  
Author(s):  
Joel I. Dulebohn ◽  
Béatrice Van Vlierberge ◽  
Kris A. Berglund ◽  
Ronald B. Lessard ◽  
Jeong-a Yu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Lanthanide Complex ◽  
Molecular Assembly ◽  
Electronic Energy ◽  
Lanthanide Ion ◽  
Europium Ion ◽  
Host Interactions ◽  
Porous Networks ◽  
Molecular Composites ◽  
Intense Luminescence

ABSTRACTSol-gel derived molecular composites exhibiting intense luminescence, induced from efficient energy transduction processes, have been prepared. The composites are comprised of an Eu3+⊂ 2.2.1 cryptate complex or native Eu3+ ion embedded in sol-gel derived titania glass films. The titania glasses contain interconnected porous networks that permit the diffusion of exogenous substrates, such as the salts of benzoic and 4-tert-butylbenzoic acids, through the film. Interaction of the substrate with the embedded lanthanide complex is indicated by enhanced luminescence from the lanthanide ion. The carboxylic acid salts whose electronic excited states are produced upon capture of incident photons, undergo facile transfer of their electronic energy to the lanthanide ion. By monitoring europium ion luminescence, the diffusion constants of the benzoate and 4-tert-butylbenzoate salts have been measured. Although the diffusion of the 4-tert-butylbenzoate is slower than that of benzoate, the overall higher sensitivity of the former is consistent with hydrophobic guest-host interactions. These new molecular composites relying on the immobilization of an absorption-energytransfer- emission molecular assembly in porous, optically transparent ceramic glasses may be useful in the design of practical sensing devices.

The mechanism of the excited-state multiple proton transfer reaction for 3-Me-2,6-diazaindole in aqueous solution

2018 ◽  
Vol 5 (18) ◽  
pp. 2749-2753 ◽  
Author(s):  
Jin-Dou Huang ◽  
Huipeng Ma
Keyword(s):  
Aqueous Solution ◽  
Excited State ◽  
Potential Energy ◽  
Proton Transfer ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Potential Energy Curves ◽  
Water Molecules

The potential energy curves show that(2,6-aza)Indin aqueous solution undergoes a quadruple-proton transfer reaction with the assistance of three water molecules.

scholarly journals Excited States of Gold(I) Compounds, Luminescence and Gold-Gold Bonding

1994 ◽  
Vol 1 (5-6) ◽  
pp. 459-466 ◽  
Author(s):  
John P. Fackler ◽  
Zerihun Assefa ◽  
Jennifer M. Forward ◽  
Richard J. Staples
Keyword(s):  
Aqueous Solution ◽  
Excited State ◽  
Triplet State ◽  
Excited States ◽  
Ground State ◽  
Superoxide Anion ◽  
Direct Interaction ◽  
Water Soluble ◽  
State Behavior ◽  
Β Carotene

It has long been established by Khan that the superoxide anion, O2-, generates singlet oxygen, O21Δg, during dismutation. Auranofin, gold-phosphine thiols, β-Carotene, and metal-sulfur compounds can rapidly quench singlet O2. The quenching of the O21Δg, which exists at 7752 cm-1 above the ground state triplet, may be due to the direct interaction of the singlet O2 with gold(I) or may require special ligands such as those containing sulfur coordinated to the metal. Thus we have been examining the excited state behavior of gold(I) species and the mechanisms for luminescence. Luminescence is observed under various conditions, with visible emission ranging from blue to red depending on the ligands coordinated to gold(I). Triplet state emission can be found from mononuclear three coordinate Au(I) species, including species which display this behavior in aqueous solution. A description is given of the luminescent three coordinate TPA (triazaphosphaadamantane) and TPPTS (triphenylphosphine-trisulfonate) complexes, the first examples of water soluble luminescent species of gold(I).

Synthesis and Characterization of Organic Dye Doped Silica Glasses

1992 ◽  
Vol 271 ◽  
Author(s):  
Ilzoo Lee ◽  
Josephine Covino ◽  
Michael D. Seltzer
Keyword(s):  
Organic Dyes ◽  
Sol Gel ◽  
Adsorbed Water ◽  
Alcohol Solution ◽  
Water Molecules ◽  
Dye Molecules ◽  
Silica Glasses ◽  
Sol Gel Process ◽  
Higher Temperature

ABSTRACTThe sol-gel process was used to incorporate organic dyes including Rhodamine 6G (Rh6G), 2-(4-pyridyl)-5-(4-phenyl) oxazole (4PyPO) and the n-methyl tosylate salt of 2-(4-pyridyl)-5-(4-methoxy phenyl)oxazole (4PyMPO-MePTS) in silica gel. Thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) analysis of the dye doped gels showed that the gel structure loses the adsorbed water molecules from room temperature to 150°C and decomposition of the dye molecules followed at the higher temperature. Absorption and emission of the dyes in the sol-gel glass matrix were also studied and compared with the results of the dyes in alcohol solution. The environments of the dye in silica were different than in alcohol solution.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

The Malleable Excited States of Benzothiadiazole Dyes and Investigation of their Potential for Photochemical Control

2019 ◽  
Author(s):  
Caroline C. Warner ◽  
andrea thooft ◽  
Bryan J. Lampkin ◽  
selin demirci ◽  
Brett VanVeller
Keyword(s):  
Excited State ◽  
Excited States ◽  
Polar Solvent ◽  
Nonpolar Solvent ◽  
Photochemical Degradation ◽  
Solvent Lead ◽  
Environmentally Sensitive

<p>A strategy to control the efficiency of a photocleavage reaction based on changing the nature of the excited state is presented. A novel class of photoactive compounds has been synthesized by combining the classical o-nitrobenzyl scaffold with an environmentally sensitive dye, 4-amino-nitrobenzothiazole. Irradiation in a polar solvent lead to an excited state that is inoperative for photochemistry whereas excitation in a nonpolar solvent lead to an excited state that is photochemically active. A photochemical degradation appears to be the preferred process in contrast to the intended photocleavage process.</p>

Excited State Tracking During the Relaxation of Coordination Compounds

2018 ◽  
Author(s):  
Juan Sanz García ◽  
Martial Boggio-Pasqua ◽  
Ilaria Ciofini ◽  
Marco Campetella
Keyword(s):  
Excited State ◽  
Excited States ◽  
Potential Energy Surfaces ◽  
Photochemical Reactions ◽  
Complex Nature ◽  
Electronic Excited States ◽  
Ruthenium Nitrosyl ◽  
State Tracking ◽  
Energy Surfaces ◽  
Electronic Wavefunction

<div>The ability to locate minima on electronic excited states (ESs) potential energy surfaces (PESs) both in the case of bright and dark states is crucial for a full understanding of photochemical reactions. This task has become a standard practice for small- to medium-sized organic chromophores thanks to the constant developments in the field of computational photochemistry. However, this remains a very challenging effort when it comes to the optimization of ESs of transition metal complexes (TMCs), not only due to the presence of several electronic excited states close in energy, but also due to the complex nature of the excited states involved. In this article, we present a simple yet powerful method to follow an excited state of interest during a structural optimization in the case of TMC, based on the use of a compact hole-particle representation of the electronic transition, namely the natural transition orbitals (NTOs). State tracking using NTOs is unambiguously accomplished by computing the mono-electronic wavefunction overlap between consecutive steps of the optimization. Here, we demonstrate that this simple but robust procedure works not only in the case of the cytosine but also in the case of the ES optimization of a ruthenium-nitrosyl complex which is very problematic with standard approaches.</div>

scholarly journals Ground- and excited-state characteristics in photovoltaic polymer N2200

RSC Advances ◽  
2021 ◽  
Author(s):  
Guanzhao Wen ◽  
Xianshao Zou ◽  
Rong Hu ◽  
Jun Peng ◽  
Zhifeng Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Steady State ◽  
Excited States ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Functional Theory ◽  
Time Resolved ◽  
Dependent Density

Ground- and excited-states properties of N2200 have been studied by steady-state and time-resolved spectroscopies as well as time-dependent density functional theory calculations.

Sign in / Sign up

Export Citation Format

Share Document