New insights into the vibrational and optical signatures of trans-stilbene via integrated experimental and quantum mechanical approaches

Abstract

The structure, spectroscopic parameters and optical properties of stilbene have been investigated by a computational protocol including suitable treatment of anharmonic contributions together with new experimental results. A full reproduction of the 500-3500 cm(-1) IR spectrum has been possible using the VPT2 approach and new insights are provided in the 6000 cm(-1) region where typical signatures have been characterized as a set of overtones and combination bands. Vibrational contributions to electronic transitions have been taken into account to simulate the optical (absorption and emission) properties of stilbene. Spectra simulated by employing the state-of-the-art Adiabatic Hessian model coupled to global hybrid functionals are in remarkable agreement with their experimental counterparts and the inclusion of Herzberg-Teller contributions further improves the results with respect to those delivered by the basic Franck-Condon model.

Ultrafast trans → cis Photoisomerization Dynamics of Alkyl-Substituted Stilbenes in a Supramolecular Capsule

“…The lack of a vibronic structure for compound 5 reflects the nonplanar equilibrium geometry of this molecule due to steric crowding of the ortho -substituted methyl groups, which rotates the phenyl rings and disrupts conjugation along the backbone of the molecule . Spectra for the other compounds all have essentially the same vibronic progression as unsubstituted trans -stilbene, which is planar in solution. − …”

Insights into the Optical Properties of Triarylboranes with Strongly Electron‐Accepting Bis(fluoromesityl)boryl Groups: when Theory Meets Experiment

“…The phosphorescence spectrum of 2 was simulated including vibronic coupling within the Adiabatic Hessian (AH) model. This model, which explicitly includes mode‐mixing between fundamental and excited states, reproduces accurately the optical properties of molecular systems . To ensure a sufficient spectrum progression (>90 %), normal modes with the lowest energies were neglected in the vibronic treatment.…”

“…This model, which explicitly includes mode-mixing between fundamental and excited states, reproduces accurately the optical properties of molecular systems. [75][76][77][78][79][80] To ensure a sufficient spectrum progression (> 90 %), normal modes with the lowest energies were neglected in the vibronic treatment. Molecular orbitals (MO) were visualized with the GaussView package.…”

Ground-State Geometry and Vibrations of Polyphenylenevinylene Oligomers

“…This is consistent with very small deplanarization energy gain (if any), so that intermolecular steric interactions easily planarize the molecules. Taking into account large uncertainty of experimental determination of BLA and dihedrals, vibrational spectroscopy becomes an important tool for indirectly probing the geometry of PPV oligomers using both empirical − and first-principles − ,, models to match experimental spectra. − For the high-frequency region (>400 cm –1 ), Raman spectra of PPV are well reproduced by harmonic approximation with scaled DFT frequencies. They are dominated by two strong Raman bands: , the band at 1600 cm –1 corresponds to the BLA mode (alternating stretching of bonds), whereas the band at 1200 cm –1 has a more complex nature.…”