Theory and computations of two-photon absorbing photochromic chromophores

Abstract

KEYWORDSExponential growth in information technology generates ever increasing amounts of data, making recording density of the storage media crucially important. Two-photon absorption was proposed as a basis for high-density multi-layer technology for optical memory and logic devices. This technology suggests to use polymers, doped with photochromic compounds that undergo a reversible photoinduced isomerization, or photoswitching. In this review we consider recent theoretical works and benchmarking studies of the DFT-based methods, capable to predict two-photon absorption (2PA) and photochemical activity, Next we review the applications of these methods to design a prototype molecule that combines the photonmode recording property of photochromic compounds with large 2PA cross-section. We conclude that a posteriori Tamm-Dancoff approximation to the second order CEO approach in Density Functional Theory is the powerful tool for both quantitative predictions and qualitative understanding of the excited state processes in photophysics and photochemistry. We also emphasize general principles for the rational design of a two-photon operated photoswitch.TDDFT Organic photochemistry Photocyclization Photoinduced reactions Two-photon absorption State-to-state transition dipoles

Three-Photon Spectroscopy of Porphyrins

“…The main challenge is the computation of the transition dipole moments μ ij connecting the excited states ( i , j ≠ 0). In this work, we used a method based on TDDFT with a posteriori Tamm–Dancoff approximation, ,, which has been proven successful in predicting 2PA in porphyrins. , It should be mentioned that multiple formulas for calculations of multiphoton absorption cross sections have appeared in the literature, using different systems of units, line shapes, conversion factors, etc. The formulas used in our calculations are discussed in the SI (Section S5).…”

“…The quantum chemistry calculations were performed using in-house-modified Gaussian 09 in conjunction with M05-QX exchange–correlation functional . The SDD Stuttgart effective core potentials were used for the metal atoms, while the D95 basis set was used for all other elements to prevent artificial Rydberg contributions to the valence excited states. ,, For all porphyrins, 22 excited states were calculated using time-dependent density functional theory (TDDFT). In all calculations, the solvent effects were included using the dielectric continuum model in the solvent model density (SMD) parameterization, as implemented in Gaussian 09.…”

“…The 3PA spectra of several Pt complexes of porphyrins in 1200–2000 nm range were measured by the method of 3P-excited phosphorescence, derived from the technique that has been used by us previously for similar 2PA measurements . To interpret the spectroscopic results, we developed a four-state model specific for porphyrins and used it in conjunction with a more quantitative computational approach, − which has already been proven successful in predicting 2PA spectra of similar porphyrinoids. , This computational method has been able to achieve excellent agreement with experiment, while the qualitative theoretical analysis allowed us to develop guidelines for future structural optimizations of porphyrins to achieve improved 3P performance.…”

Adsorption of Glyoxal (CHOCHO) and Its UV Photolysis Products on the Surface of Atmospheric Ice Nanoparticles. DFT and Density Functional Tight-Binding Study

“…Although photochemical reactions take place on the excited state potential energy surface, their computational study is rather involved, 59,60 and for some steps activation berries on the ground state can suffice. 61−63 In order to estimate the probability of the reaction steps above, we calculated the energies and thermodynamic parameters for these reaction steps.…”

Two-Photon Absorbing Molecules as Potential Materials for 3D Optical Memory

“…In particular, we focus on molecular materials, and, thereby, topics of devices, for example, laser system, optical system, and so on, which have been introduced in some excellent reviews [2,34], are not included. The significant studies on theory and calculations mainly using a DFT (density functional theory) method, which are useful in the design of new two-photon absorbing molecules, have also been reported [35][36][37] and reviewed [38]. …”