Halochromic and hydrochromic squaric acid functionalized perylene bisimide

2015 ◽  
Vol 51 (36) ◽  
pp. 7661-7664 ◽  
Author(s):  
Takeshi Maeda ◽  
Frank Würthner
Keyword(s):  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Solvent Polarity ◽  
Squaric Acid ◽  
Perylene Bisimide

A squaric acid functionalized perylene bisimide senses solvent polarity, pH and humidity through the intramolecular charge transfer initiated by protonation/deprotonation.

scholarly journals Crystal Structures and Optical Properties of Two Novel 1,3,5-Trisubstituted Pyrazoline Derivatives

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 467
Author(s):  
Qi Feng ◽  
Wenhui Huan ◽  
Jiali Wang ◽  
Jiadan Lu ◽  
Guowang Diao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Charge Transfer ◽  
Solid State ◽  
Physical Properties ◽  
Intramolecular Charge Transfer ◽  
Solvent Polarity ◽  
Dihedral Angles ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography

Two novel 1,3,5-trisubstituted pyrazoline derivatives—1-acetyl-3-(4-methoxyphenyl)-5-(6-methoxy-2-naphthyl)-pyrazoline (2a) and 1-(4-nitrophenyl)-3-(4-methoxyphenyl)-5-(6-methoxy-2-naphtyl)-pyrazoline (2b)—were synthesized and their structures were determined by single crystal X-ray crystallography. Both of the two crystals exhibit twisted structures due to the large dihedral angles between the pyrazolinyl ring and the aromatic ring at the 5-position (88.09° for 2a and 71.26° for 2b). The optical–physical properties of the two compounds were investigated. The fluorescent emission of 2b arises from the 1,3-disubstituted pyrazoline chromophores and exhibits a red shift in polar solvents and solid-state, which could be attributed to photo-induced intramolecular charge transfer (ICT) from N1 to C3 in the pyrazoline moiety and the intermolecular interactions within the crystal. The fluorescent emissions of 2a (λmax 358–364 nm) in solvents and solid-state both come from 6-methoxy-2-naphthyl chromophores, which are fairly insensitive to the solvent polarity.

Direct evidence of solvent polarity governing the intramolecular charge and energy transfer: ultrafast relaxation dynamics of push–pull fluorene derivatives

2019 ◽  
Vol 21 (21) ◽  
pp. 11087-11102 ◽  
Author(s):  
Afeefah U. Neelambra ◽  
Chinju Govind ◽  
Tessy T. Devassia ◽  
Guruprasad M. Somashekharappa ◽  
Venugopal Karunakaran
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Emission Spectroscopy ◽  
Direct Evidence ◽  
Transient Absorption ◽  
Intramolecular Charge Transfer ◽  
Solvent Polarity ◽  
Relaxation Dynamics ◽  
Ultrafast Relaxation ◽  
Absorption And Emission Spectroscopy

The occurrence of intramolecular charge transfer along with energy transfer controlled by the polarity of solvent is revealed by femtosecond and nanosecond transient absorption and emission spectroscopy.

Fluorescence of Trans-4-Cyano-4′-dimethylaminostilbene; No Evidence for a TICT State

1983 ◽  
Vol 38 (8) ◽  
pp. 928-936 ◽  
Author(s):  
Henry Gruen ◽  
Helmut Görner
Keyword(s):  
Charge Transfer ◽  
Double Bond ◽  
Relaxation Process ◽  
Singlet State ◽  
Intramolecular Charge Transfer ◽  
Solvent Polarity ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Dual Emission ◽  
Fluorescence Maximum

AbstractThe fluorescence properties of trans-4-cyano-4′-dimethylaminostilbene (trans-1) and a rigid analogue, in which the dimethylaminophenyl group is replaced by an indoline ring, trans-l-(4-cyanophenyl)-2-(5-[2,3-dihydro]N-methylindolyl)ethylene (trans-2) were studied in 20 solvents. The quantum yields of fluorescence (Φf) and of trans→cis photoisomerization (Φt→c) as well as the fluorescence maximum (ν̃f) and the bandwidth (⊿ν̃f) were examined. The activation energies (range: 3.5-7.8 kcal/mol) obtained from <2>f and <£t_c measurements are nearly the same for 1 and 2 in a given solvent. Φf , ν̃f and ⊿ν̃f as a function of solvent polarity and temperature show similar trends for 1 and 2. No dual emission was observed for either of the cyanostilbenes. These findings indicate that a twisted intramolecular charge transfer (TICT) state is not involved in the relaxation process of the first excited trans singlet state (1t*). The main deactivation pathway of 1t* competing with fluorescence is trans→cis photoisomerization by twisting about the C = C double bond in the first excited singlet state for both.

scholarly journals Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

2010 ◽  
Vol 6 ◽  
pp. 992-1001 ◽  
Author(s):  
Ritesh Nandy ◽  
Sethuraman Sankararaman
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Linear Correlation ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Solvent Polarity ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor ◽  
Stokes Shifts

Several 2-(phenylethynyl)triphenylene derivatives bearing electron donor and acceptor substituents on the phenyl rings have been synthesized. The absorption and fluorescence emission properties of these molecules have been studied in solvents of different polarity. For a given derivative, solvent polarity had minimal effect on the absorption maxima. However, for a given solvent the absorption maxima red shifted with increasing conjugation of the substituent. The fluorescence emission of these derivatives was very sensitive to solvent polarity. In the presence of strongly electron withdrawing (–CN) and strongly electron donating (–NMe2) substituents large Stokes shifts (up to 130 nm, 7828 cm−1) were observed in DMSO. In the presence of carbonyl substituents (–COMe and –COPh), the largest Stokes shift (140 nm, 8163 cm−1) was observed in ethanol. Linear correlation was observed for the Stokes shifts in a Lippert–Mataga plot. Linear correlation of Stokes shift was also observed with E T(30) scale for protic and aprotic solvents but with different slopes. These results indicate that the fluorescence emission arises from excited state intramolecular charge transfer in these molecules where the triphenylene chromophore acts either as a donor or as an acceptor depending upon the nature of the substituent on the phenyl ring. HOMO–LUMO energy gaps have been estimated from the electrochemical and spectral data for these derivatives. The HOMO and LUMO surfaces were obtained from DFT calculations.

Über die Löschung von „Twisted Intramolecular Charge Transfer" (TICT)-Fluoreszenzen durch äußere Schweratom-Störer

1984 ◽  
Vol 39 (1) ◽  
pp. 41-48 ◽  
Author(s):  
W. Rettig ◽  
M. Zander
Keyword(s):  
Distribution Function ◽  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Methyl Iodide ◽  
Energy Gap ◽  
Intramolecular Charge Transfer ◽  
Twist Angle ◽  
Heavy Atom ◽  
Solvent Polarity ◽  
Tict States

The quenching by methyl iodide and ethyl bromide of the TICT fluorescence of N-(p-cyanophenyl)- carbazole (II) and N-(l-naphthyl)-carbazole (III) has been studied in solvents of different polarity. It is found that the heavy atom induced bimolecular fluorescence quenching increases with increasing energy of the TICT fluorescence transition, contrary to the energy-gaprule, and that TICT states are much less readily quenched than locally excited (LE) states. These results are explained by assuming a very small S-T energy gap for TICT states and a solvent polarity dependent distribution function for the intramolecular twist angle.

A TWO-FORM DESCRIPTION OF PUSH-PULL MOLECULES: CORRELATIONS BETWEEN STRUCTURE, INTRAMOLECULAR CHARGE TRANSFER AND (HYPER) POLARIZABILITIES

1996 ◽  
Vol 05 (04) ◽  
pp. 757-765 ◽  
Author(s):  
M. BARZOUKAS ◽  
A. FORT ◽  
M. BLANCHARD-DESCE
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Intramolecular Charge Transfer ◽  
Ground States ◽  
Solvent Polarity ◽  
Reaction Field ◽  
Donor Acceptor ◽  
Semi Empirical ◽  
Relevant Factors ◽  
Acceptor Molecules

We present a quantum two-form two-state description of donor-acceptor molecules. We single out relevant factors that are characteristic of the molecule and its environment. In addition, we define a parameter which rules the geometry of both ground and excited states. Also, this parameter is proportional to the change in dipole between excited and ground states. We show that correlations between (hyper)polarizabilities and this parameter reproduce remarkably well semi-empirical predictions. We extend this model in order to account for the solvent reaction field. This model helps in the understanding of the dependencies of (hyper)polarizabilities on solvent polarity.

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