Tuning of the Electro-Optical Properties of Tetraphenylcyclopentadienone via Substitution of Oxygen with Sterically-Hindered Electron Withdrawing Groups

Abstract

In this report, the substitution of the oxygen group (=O) of Tetraphenylcyclopentadienone with =CR 2 group (R = methyl ester or nitrile) was found to have tuned the electro-optical properties of the molecule. Although both groups are electrons withdrawing in nature, their absorption from UV-vis spectra analysis was observed to have been blue-shifted by methyl ester substitution and red-shifted by nitrile substitution. Interestingly, these substitutions helped to enhance the overall intensity of emission, especially in the context of methyl ester substitution whereby the emission was significantly boosted at higher concentrations due to hypothesized restrictions of intramolecular motions. These observations were explained through detailed descriptions of the electron withdrawing capability and steric properties of the substituents on the basis of density functional theory calculations.

Novel Fluorescent Azacyanine Compounds: Improved Synthesis and Optical Properties

“…The electron-withdrawing groups do not have such a stabilization effect on the positive charge of the nitrogen atom and therefore do not change the energy gap. It is usual to see such shifts in the positions of absorption maxima, depending on the identity of the substitution. , Very similar effects were observed by Enchev et al They reported that although replacing the hydrogen with a chlorine was shifting the absorption maxima of their parent azacyanine by only 9 nm, replacing it with a methoxy group was shifting it about 30 nm. On the other hand, broadness of the absorption peaks is due to the presence of several vibrational and rotational states corresponding to the ground state and the excited states. , The presence and the identity of the substitution of the ring system might be one of the possible reasons behind the observed differences in broadness.…”

“…It is usual to see such shifts in the positions of absorption maxima, depending on the identity of the substitution. 34 , 35 Very similar effects were observed by Enchev et al 18 They reported that although replacing the hydrogen with a chlorine was shifting the absorption maxima of their parent azacyanine by only 9 nm, replacing it with a methoxy group was shifting it about 30 nm. On the other hand, broadness of the absorption peaks is due to the presence of several vibrational and rotational states corresponding to the ground state and the excited states.…”

Tetraphenylcyclopentadiene-based conjugated microporous polymers for high-performance energy storage carbons

“…Consequently, we selected trichlorotriazine (TCT) to carry out nucleophilic substitution reactions with 2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-one (CP) and 2-(2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-ylidene) malononitrile (CPM) to obtain triazine-based CP-TCT and CPM-TCT CMPs, respectively (Scheme 1). Precursors CP and CPM were synthesized in good yields following literature procedures 70,71 as presented in the synthetic routes in Schemes S1 and S2 and The CMPs containing the triazine moiety were constructed using the metal-free Friedel-Crafts simple polymerization reaction of TCT with both CP and CPM, in o-dichlorobenzene at 140 °C, using a methane-sulfonic acid catalyst, as illustrated in Schemes 1, S3, and S4 †. The reaction yields of the prepared polymers CP-TCT and CPM-TCT CMPs were 67.3% and 53.5%, respectively.…”

“…Consequently, we selected trichlorotriazine (TCT) to carry out nucleophilic substitution reactions with 2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-one (CP) and 2-(2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-ylidene) malononitrile (CPM) to obtain triazine-based CP-TCT and CPM-TCT CMPs, respectively (Scheme 1). Precursors CP and CPM were synthesized in good yields following literature procedures 70,71 as presented in the synthetic routes in Schemes S1 and S2 and Fig. S1–S6†.…”

“…66,67 Also, they have been used as intermediates for the preparation of polyphenylene dendrimers and gelators that absorb and emit within the UV-visible range. [68][69][70] Therefore, in this context we have prepared porous carbon materials through calcination and KOH activation at 700 °C of novel CP-TCT and CPM-TCT CMPs, which were synthesized via the Friedel-Crafts coupling of tetraphenylcyclopentadienone (CP) and tetraphenylcyclopentadienylidene malononitrile (CPM) with cyanuric chloride (Scheme 1).…”