Triple Exciplex Research Articles

Photophysical processes of 1,3-dicarbazolypropane

The photophysical processes of 1,3-dicarbazolypropane (DCZP), which possesses two fluorogen, carbazoly, and one carbonic chain composed of three carbon atoms, were studied. The formation of intermolecular excimer, intramolecular excimer and triple exciplexes have been investigated in the system of DCZP and 1,4-dinitrilebenzene (DNB) with steady state fluorescence spectroscopy. The experimental results show that with the addition of DNB into the lower concentration solution of DCZP in benzene, the fluorescence of intramolecular excimer of DCZP, (D-D)*, is quenched while the ((D-D)A)* type triple exciplex (one molecule of DCZP with one molecule of DNB) is formed and with the addition of DNB into higher concentration solution of DCZP, the formation of (DDA)* type triple exciplex (two molecules of DCZP with one molecule of DNB) is also confirmed.

Photophysical processes of a copolymer containing naphthalene and carbazole rings

The photophysical processes of copolymer formed by copolymerization of β-naphthyl-methacrylate (NMA) with vinylcarbazole (VCZ) were studied. The results show that when the solution of copolymer (NMA–VCZ) in THF is located in a low concentration range (about 10 −8 mol/l), the fluorescence emission is in good agreement with that of NMA monomer and the excimer is formed with gradual increase in concentration of copolymer (NMA–VCZ). The fluorescence of copolymer (NMA–VCZ) can be efficiently quenched both by electron donors and acceptors where the quenching effects follow the Stern–Volmer equation. The dimolecular exciplex between copolymer (NMA–VCZ) and N, N-dimethylaniline (DMA) is formed and the triple exciplex is also observed in the same system.

TIME-RESOLVED FLUORESCENCE STUDY OF TRIPLE EXCIPLEX FORMED IN THE SYSTEM OF POLY(2-VINYL) NAPHTHALENE AND TEREPHTHALIC DIMETHYLESTER

An intramolecular excimer of poly(2- vinyl) naphthalene was formed by non-adjacent chromophores interaction, then a triple exciplex was formed by interaction with the acceptor molecule further in dilute solution. The lifetime of the intramolecular excimer of poly(2- vinyl) naphthalene, τ_2 = 18.83 ns and the rate constant for the triple exciplex formation, k_7 = 4. 18× 10~9 (mol/L)~(-1)s~(-1), under diffusion-control were measured. An excimer or an exciplex could be an intermediate of the triple exciplex formation. A theoretical model of the triple exciplex formation is proposed.

STEADY-STATE AND TIME-RESOLVED FLUORESCENCE STUDY OF TRIPLE EXCIPLEX IN THE SYSTEM OF POLYACENAPHTHALENE AND TEREPHTHALIC DIMETHYLESTER

Triple exciplex formed between polyacenaphthalene and terephthalic dimethylester (TDE) has been studied by means of the steady-state and time-resolved fluorescence spectra. The theoretical model of the triple exciplex formation for a flexible polymer chain in a dilute solution has been proposed. The fluorescence decays of the monomer, the exciplex and the triple exciplex obey a double exponential rule in the pbotophysical processes of the triple exciplex formation. The association rate constant of the exciplex formation is k_3=6.0×10~9s~(-1)(mol/L)~(-1); the association rate constant of the triple exciplex formation is k_6=5.2×10~7s~(-1). A mechanism for the triple exciplex formation from the exciplex to the triple exciplex has been proved through the noncrystal films corresponding to the same concentrations of the solution systems and the fluorescence lifetimes of the intramolecular excimer.

Quenching of the 1(1-pyrenyl), 3n(3-methylindole)propane exciplex by m-dicyanobenzene. Formation of an emitting terplex consisting of three different components

The intramolecular exciplex 1(1-pyrenyl), 3N(3-methylindole)propane is quenched by m-dicyanobenzene. The pyrene and the exciplex fluorescence is quenched and their respective rate constants equal 1.5 × 10 10 l mol −1 s −1 and 1.1 × 10 10 l mol −1 s −1. The quenching of the exciplex results in the emission of a new species, which does not arise from exciplex substitution, but can be ascribed to a triple exciplex (mDCB −1 Py-C 3H 6-In +).

Quenching of intramolecular exciplexes by pyridine and methylpyridines suggesting triple exciplex (D'DA)* formation

Quenching of intramolecular exciplexes by pyridine and methylpyridines suggesting triple exciplex (D'DA)* formation

Fluorescence quenching of intramolecular exciplex by pyridine and formation of triple exciplex

Intramolecular exciplex fluorescence of (9.10-dicyanoanthryl)-(CH 2) 3-(1-or 2-naphthyl) was quenched by pyridine and/or γ-picoline. Two-component decay of the exciplex (DA)* fluorescence demonstrates the formation of a new type of triple exciplex (DD́A)*.

The effect of solvent on exciplex emission from pyrene—tributylamine and anthracene—tributylamine systems

The exciplex emissions from the pyrene—tributylamine (TBA) and anthracene—TBA systems have been found to undergo a red shift in solvents of higher dielectric constants. From these shifts it has been estimated that the extent of charge transfer is 66% in the pyrene—TBA system, while it is over 80% in the anthracene—TBA system. In aromatic hydrocarbon solvents the exciplex emission was found to undergo a red shift and an intensification in the order benzene > p-xylene > mesitylene. This has been attributed to triple exciplex formation, for which the equilibrium constants between the exciplex and the aromatic solvents have been found to be 3.2 × 10 −2 (benzene), 2.2 × 10 −2 ( p-xylene) and 2.2 × 10 −2 (mesitylene) for the pyrene—TBA system, while for the anthracene—TBA system the equilibrium constants were 8.3 × 10 −3 (benzene) 8.3 × 10 −3 ( p-xylene) and 6.6 × 10 −3 (mesitylene). A tentative explanation for the effect of aromatic hydrocarbon solvents on exciplex emission has been suggested. In alcoholic solvents the exciplex emissions were blue shifted owing to the formation of hydrogen bonded complexes between the exciplex and the alcohols. The pyrene—TBA system forms much stronger hydrogen bonds with alcohols than the anthracene—TBA system. This was considered to indicate the participation of the lone pair electrons at the nitrogen of TBA in hydrogen bond formation.

Time-Resolved Fluorescence Study of Exciplex and Triple Exciplex in 1,4-Dicyanobenzene and Alkylnaphthalenes

Abstract Exciplex (DA)* and triple exciplex (DDA)* formation between 1,4-dicyanobenzene (DCB) and alkylnaphthalenes was investigated by steady-state and nanosecond time-resolved fluorescence spectroscopies at room temperature. Typical two-component decay of the exciplex and the fluorescence rise of the triple exciplex were observed in dioxane solutions of DCB and several alkylnaphthalenes. The results imply a significant dissociation process of (DDA)* to (DA)*. Triple exciplex formation via excimer (DD)* was proposed to be significant in a concentrated solution of alkylnaphthalene (>10−1 M), while the triple exciplex was formed via the exciplex in a dilute solution of the electron donor.

Electronic Interactions in Triple Exciplex of the 1,4-Dicyanobenzene and Naphthalene System

Abstract Semiempirical SCF-MO-CI caluculation was carried out for the 1,4-dicyanobenzene (DCB) and naphthalene system which is known to form exciplex (DA)* and triple exciplex (D2A)*. Potential energy curves of the electronic interactions between excimer and electron acceptor molecule, and between exciplex and electron donor molecule were constructed. The results show that the array of component molecules in the triple exciplex is DDA, and the stabilization energy of triple exciplex is ≈0.4 eV from the excimer and ≈0.2 eV from the exciplex. They are in line with results reported on the experiment of exciplex and triple exciplex formation.

Time-resolved fluorescence study of triple exciplex in 1,3-dinaphthylpropane and 1,4-dicyanobenzene

The triple exciplex formation between two naphthyl moieties in 1,3-dinaphthylpropane (ββ- and βα-DNP) and 1,4-dicyanobenzene (DCB) was studied by a nanosecond time-resolved fluorescence spectroscopy. The fluorescence of a dioxane or chloroform solution of ββ-DNP and DCB consists of three fluorescence spectra of the intramolecular excimer, the exciplex (DA)* and the triple exciplex (DDA)*. The triple exciplex was not formed via the excimer, but formed via the exciplex.

Time-resolved fluorescence study of triple exciplex formation in 1,3-dinaphthylpropane and 1,4-dicyanobenzene

Time-resolved fluorescence study of triple exciplex formation in 1,3-dinaphthylpropane and 1,4-dicyanobenzene