Molecular logic gates based on benzo-18-crown-6 ether of styrylquinoline: a theoretical study

Abstract

In the present work, we examine the possibility of a benzo-18-crown-6 ether of styrylquinoline molecule (1) in acetonitrile solvent to act as a sensor for the Ca cation and as a molecular logical gate. DFT and TDDFT calculations are carried out using the M06-2X and the PBE0 functionals. The quinoline moiety is an electron donor and an H receptor, while the crown ether is a Ca receptor forming host-guest complexes with Ca. The calculations show that there are 8 thermally stable forms, i.e., trans and cis isomers of neutral (1), protonated (1H+), complexed with Ca (1Ca++), and both protonated and Ca complexed (1H+Ca++), with different absorption and emission spectra, and which can be interconverted from one form to another. The addition of H and/or Ca to 1 results in variation of the oscillator strength of the major absorption and emission peaks as well as in significant shifts of the major absorption and emission peaks including shifting from the vis spectral area to UV and vice versa. Consequently, 1 is a candidate for a sensor for the Ca cation. Furthermore it is shown that 1 can act as a molecular optical switch owing to its ability to be reversibly protonated and/or Ca complexed with substantial accompanying differences in the spectral properties. Similarly, 1 can be used as a sensor molecular logic gate, in which using H and Ca and irradiation as input, the emission output at 500, 470, 430, and 407 nm can be utilized as output to build AND, NOR, XOR, XNOR, INHIBIT, and IMPLICATION logic gates.

Theoretical study of the photophysical processes of a styryl‐bodipy derivative eliciting an AND molecular logic gate response

“…However, a significant rise of information processing molecular devices is expected in the forthcoming years . Theoretical studies aiming to provide experimentalists with information regarding a potential MLG candidate or to gain insight into experimental findings can play a significant role in the field of MLG …”

“…[15] Theoretical studies aiming to provide experimentalists with information regarding a potential MLG candidate or to gain insight into experimental findings can play a significant role in the field of MLG. [27][28][29][30][31] Photoinduced electron transfer (PET) is particularly useful, as the signal, depending on the special circumstances, is either an "on-off" or "offon" type, [32] resulting in a well-defined "digital" response: PET produces very sharp changes in the signal intensity, while keeping the emission wavelength unchanged. [9] Internal charge transfer (ICT) [33,34] on the other hand can be modulated in such a way as to generate changes in the absorption or emission wavelengths, which proved to be very useful for superposed logic gates, sometimes referred to as wavelengthreconfigurable logic gates.…”

The solvent effect on a styryl‐bodipy derivative functioning as an AND molecular logic gate

“…This methodology predicted the best results for 1 , 1‐M 2+ , and 2 in acetonitrile solvent compared to the available experimental data and for this reason it is applied for the present calculations. Moreover, its applicability has been tested previously on calculations of the absorption and emission spectra in similar systems, including complexes of crown ethers …”

“…As a result, in response to these modulations, molecules can exhibit differences in their ground or excited electronic states, with accompanying modifications in the absorption and/or emission intensity and wavelength. Such changes can be related to the operation of fluorescence chemosensors, molecular switches, and logic gates (via the familiar Boolean logic where the modulators correspond to the inputs and the observed changes correspond to the outputs) . As a consequence, the field of molecular logic gates and generally of chemosensors and molecular switches is very active and many research groups around the world work on these subjects …”

“…Which is the key factor for the retaining of the emission in all calculated species regardless of the conditions? It should be noted that our previous studies have provided us with all necessary know‐how of computational approach for successful prediction of molecular logic gate candidates and molecular switches, which will be used in the present study.…”