Effect of Chain Length on the Photophysical Properties of Pyrene-Based Molecules Substituted with Extended Chains

Abstract

The important role played by organic conjugated compounds in the fields of electronics and optoelectronics has led to a vast field of research concerned with synthesizing various complex structures where pi-pi stacking plays a vital role. Pyrene-based molecules are examples of compounds which allow efficient charge transfer through pi-pi molecular stacking. Photophysical studies of such compounds have shown similar behavior as that of pyrene, even though they bear two additional conjugated rings and four long alkyl chains. Chain length may have played an effective role in influencing the pi-pi molecular stacking of such molecules. In continuation of our earlier work (Moustafa, R. M.; Degheili, J. A.; Patra, D.; Kaafarani, B. R. J. Phys. Chem. A 2008, 113, 1235-1243), we hereby synthesize and investigate the role of the chain lengths on the photophysical aspects of 2,11-di-tert-butyl-6,7,15,16-tetrakis(alkoxy/alkythio)quinoxaline-[2',3':9,10]phenanthro[4,5-abc]phenazine, TQPP-[t-Bu](2)-[XR](4) (X = O, S; R = C(n)H(2n+1)). Various photophysical parameters such as Stokes shift, fluorescence lifetime, fluorescence quantum yield, and radiative and nonradiative rate constants are evaluated for TQPP-[t-Bu](2)-[OR](4) and TQPP-[t-Bu](2)-[SR](4) in tetrahydrofuran. The variation of the Stokes shift, fluorescence quantum yield, and lifetime are also correlated with the number of carbons in the alkyl chain R for TQPP-[t-Bu](2)-[OR](4) and TQPP-[t-Bu](2)-[SR](4).

Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye

“…The Lippert-Mataga equation [29][30][31][32] shows that the solvent dependence of the Stokes' shift for a compound depends on the change in the dipole moment of the fluorescence moiety upon excitation, the dielectric constant, and the refractive index of the solvents being used [29][30][31][32][33][34][35]:…”

Unique role of ionic liquid [bmin][BF4] during curcumin–surfactant association and micellization of cationic, anionic and non-ionic surfactant solutions

“…A red shift was also observed after the cmc for CTAB. The Stokes' shift of curcumin in various concentrations of CTAB, SDS and TX100 was determined as the difference between absorption and emission maxima obtained from the corrected spectra on the wavenumber scale [41,42]. The plot of Stokes' shift versus surfactant concentration offered three different kinds of change, respectively, for cationic (CTAB), anionic (SDS) and neutral (TX100) surfactant solutions.…”

Realizing Near‐Infrared Laser Dyes through a Shift in Excited‐State Absorption

“…Moreover, the absorption and emission solvatochromisms were studied and TPATBC showed larger redshifts in polar solvents (Figure S3, Supporting Information). According to the Lippert–Mataga plot (Methods S2 and Figure S4, Supporting Information), [ 24–27 ] the change of the dipole moments between the S 0 and S 1 states (Δμ ge ) was calculated to be Δμ ge = 9 and 12 D for TPABC and TPATBC, respectively, suggesting a slightly higher intramolecular CT nature with the thiophene rings.…”