Design principles and action of molecular logic gates

Utilizing sulfa drugs' pH-dependent spectral modifications for designing molecular logic gates

In this study, the absorption and fluorescence characteristics of sulfa drugs, specifically Sulfadiazine (SDZ), Sulfamerazine (SMZ), and Sulfamethazine (STZ), were examined across a pH range of 1-14. The absorption and fluorescence spectra of these sulfa drugs showed significant changes depending on the pH value. Analysis of their pH-dependent absorption and fluorescence properties indicated that these sulfa drugs could used to design molecular logic gates. The absorption and fluorescence behaviors at various wavelength maxima were utilized to design IMPLICATION and Improved-INHIBIT (I-INHIBIT) molecular logic gates.

Styrene monomer as potential material for design of new optoelectronic and nonlinear optical polymers: density functional theory study

Using density functional theory, we have studied the intrinsic properties of styrene. First, we determine the optimized structures, structural parameters and thermodynamic properties to make our simulations more realistic to experimental results and check the stability. Second, we investigate optoelectronic, electronic and global descriptors, transport properties of holes and electrons, natural bond orbital analysis, absorption and fluorescence properties. Finally, we study nonlinear optical (NLO) properties: first- and second-order hyperpolarizability, second and third-order optical susceptibilities, hyper-Rayleigh scattering hyperpolarizability, electro-optical Pockel effect, direct current Kerr effects and quadratic refractive index. The bandgap energy E g = 5.146 eV and dielectric constantε r = 3.062 show that styrene is a good insulator with an average electric field value of 4.43 × 108 Vm-1. Thermodynamic findings show that our molecule is thermodynamically and chemically stable. Electron and hole reorganization energies of 0.393 and 0.295 eV, respectively, show that styrene is more favourable to hole transport than electron transport. Styrene is transparent with linear refractive index n = 1.750 and quadratic n 2 = 1.748 × 10-20 m2 W-1. At the NLO, styrene has a non-zero value ofβ H R S , which confirms the existence of first-order NLO activity. Globally the study shows that the styrene monomer is suitable for the architecture design of new polymer materials for NLO applications and optoelectronic by functionalization.

A Tutorial Review on the Fluorescent Probes as a Molecular Logic Circuit-Digital Comparator

The rapid progress in the field of fluorescent probes and fluorescent sensing material extended this research area toward more complex molecular logic gates capable of carrying out a variety of sensing functions simultaneously. These molecules are able to calculate a composite result in which the analysis is not performed by a man but by the molecular device itself. Since the first report by de Silva of AND molecular logic gate, all possible logic gates have been achieved at the molecular level, and currently, utilization of more complicated molecular logic circuits is a major task in this field. Comparison between two digits is the simplest logic operation, which could be realized with the simplest logic circuit. That is why the right understanding of the applied principles during the implementation of molecular digital comparators could play a critical role in obtaining logic circuits that are more complicated. Herein, all possible ways for the construction of comparators on the molecular level were discussed, and recent achievements connected with these devices were presented.

Fluorescent pseudorotaxanes of a quinodicarbocyanine dye with gamma cyclodextrin

Spectrophotometric titration of buffered solutions of gamma cyclodextrin (γCD) and 1,1'-diethyl,2,2'-dicarbocyanine (DDI) demonstrates extension of the known 1:2 host:guest complex to form a previously unreported 2:2 complex near the γCD solubility limit. Though DDI is predominantly hosted as a non-fluorescent H-aggregate, both complexes exist in respective equilibria with two secondary complexes hosting unaggregated DDI as 1:1 and 2:1 complexes. The 2:1 complex exhibits significant fluorescence emission, with a quantum yield six times that of DDI in organic solvents, but ten times lower than that of an analogous indodicarbocyanine. Fragment Molecular Orbital calculations suggest that the 2:1 complex has the tail-to-tail conformation, and that solvent access to the dye strongly favors photoisomerization. In the host-guest complex, γCD limits solvent access to the dye and hinders rotation of the quinolyl terminal groups, but nevertheless pairwise rotation of methine carbons within the γCD cavity likely remains as a significant nonradiative relaxation pathway for the excited state.

Synthesis, fluorescence-sensing and molecular logic of two water-soluble 1,8-naphthalimides

Two novel highly water-soluble fluorescence sensing 1,8-naphthalimides are synthesized and investigated. The novel compounds are designed on the "fluorophore-receptor₁-spacer-receptor₂" model as a molecular fluorescence probe for determination of cations and anions in 100% aqueous media. The novel probes comprising N-imide and N-phenylpiperazine or morpholine substituents are capable to operate simultaneously via ICT and PET signaling mechanism as a function of pH and to recognize selectively Cu²⁺ and Hg²⁺ over the other representative metal ions. Due to the remarkable fluorescence changes in the presence of protons, hydroxyl anions, Hg²⁺ and Cu²⁺, INH and doubly disabled INH logic gates are executed and the systems are able to act as a single output combinatorial logic circuit with four chemical inputs.