Tuning the Electronic Transition Energy of Indole via Substitution: Application to Identify Tryptophan-Based Chromophores That Absorb and Emit Visible Light

Fluorescent amino acids (FAAs) offer significant advantages over fluorescent proteins in applications where the fluorophore size needs to be limited or minimized. A long-sought goal in biological spectroscopy/microcopy is to...

Prediction of Solvatochromic Polarity Parameters for Aqueous Mixed-Solvent Systems

Solvent polarity is important data being used in solvent selections for preliminary engineering design of chemical processes. In this work, a predictive model is proposed for estimating the solvatochromic polarity of electronic transition energy (ET) of Reichardt indicator for aqueous mixtures. To validate the model, the ET values of eighteen aqueous mixtures collected from the literature were used. The predictive model provided a good estimation of ET values with an overall deviation of 2.1%, compared with an ideal model (5.1%) from the mole fraction average. The linear relationship of the contribution factor of hydrogen bond donor interactions (CFHBD) in the predictive model with Kamlet–Taft acidity was newly proposed in order to extend the model for other aqueous mixtures. The predictive model is applicable to many aqueous mixtures and simply requires three properties of pure components as: (i) ET values, (ii) gas-phase dipole moment and (iii) Kamlet–Taft acidity.

NIR-Responsive Carbon Nitride of Five-Membered Rings (C3N2) for Photoelectrochemical Biosensing

Polymeric carbon nitrides (pCN) have garnered immense attention, ranging from super-hard materials to artificial photosynthesis, due to their exceptional chemical and optoelectronic properties. The most studied C₃N₄ along with other stoichiometric pCN, such as C₃N, C₂N and C₃N₅, commonly employed a six-membered ring as the basic units; while the five-membered rings are also popular in a myriad of natural and artificial molecules with a more polarized framework and intriguing functionalities. Here, we report a facile synthesis of C₃N₂ with a topological structure of five-membered rings, endowing by far the narrowest the first electronic transition energy (0.81 eV) in pCN family. The basic imidazole unit with dangling bonds, resulting in an unusual electronic band of p-π conjugation and split molecular orbitals, was revealed in C₃N₂ by both experiments and density functional theory calculations. Moreover, a NIR-responsive photoelectrochemical (PEC) biosensor for non-transparent biosamples was constructed for the first time using C₃N₂ with outstanding performance. This work would not only open a new vista of pCN with different topological structures but also broaden the horizon of their application, such as prospective <i>in vivo</i> PEC bioassay.

NIR-Responsive Carbon Nitride of Five-Membered Rings (C3N2) for Photoelectrochemical Biosensing

Polymeric carbon nitrides (pCN) have garnered immense attention, ranging from super-hard materials to artificial photosynthesis, due to their exceptional chemical and optoelectronic properties. The most studied C₃N₄ along with other stoichiometric pCN, such as C₃N, C₂N and C₃N₅, commonly employed a six-membered ring as the basic units; while the five-membered rings are also popular in a myriad of natural and artificial molecules with a more polarized framework and intriguing functionalities. Here, we report a facile synthesis of C₃N₂ with a topological structure of five-membered rings, endowing by far the narrowest the first electronic transition energy (0.81 eV) in pCN family. The basic imidazole unit with dangling bonds, resulting in an unusual electronic band of p-π conjugation and split molecular orbitals, was revealed in C₃N₂ by both experiments and density functional theory calculations. Moreover, a NIR-responsive photoelectrochemical (PEC) biosensor for non-transparent biosamples was constructed for the first time using C₃N₂ with outstanding performance. This work would not only open a new vista of pCN with different topological structures but also broaden the horizon of their application, such as prospective <i>in vivo</i> PEC bioassay.

Dyes: quantum chemical calculation of electronic spectra

The basics of the quantum mechanical theory of the light absorption process, the simplifications of the theory in form of models and their application to dyes are reviewed. The factors governing the electronic transition energy, the intensity of the electronic transition and the vibrational fine structure of the absorption bands are examined.

"The Effects of Additive TiO2 Nanoparticles on the Optical properties of DCM Doped with PVC Thin Films "

"In this work thin films containing laser dye (DCM) doped with (PVC) were prepared using casting method. Titania (TiO2) nanoparticles also were synthesized using sol-gel technique. Different titania nanoparticle densities (0.882×1020, 1.765×1020, 2.648×1020 and 3.530×1020 cm-3) were co-doping with dye doped polymer to study the effect of this addition on the optical properties and electronic transition energy gaps in cases of both direct and indirect transitions, Absorbance spectra were measured using Spectrophotometer. Absorption and extinction coefficients as well as the refractive indices have been obtained the spectra of absorbance at the strong absorption region. It was observed from results that the allowed direct electronic transitions energy gap was decreasing from 2.22 to 2.175e.V with the increasing of titania nanoparticles density and the allowed indirect electronic transition energy gap decreasing from 2.19 to 2.13e.V.

"Synthesis and Optical Properties of Polystyrene Doped with DCM Thin Films "

"In the present work Polystyrene (PS) polymer doped with DCM laser dye thin films have been prepared on glass substrate using casting method. The final samples of PS doped with DCM thin films were treated with different annealing temperatures at (30, 40, 50, 60) oC. Optical absorption and transmission spectra of the prepared thin films were recorded using UV-VIS double beam spectrometer in the wavelength range from 190 to 1100 nm. The results shown that the allowed direct electronic transitions energy gap increased from 2.08 up to 2.25e.V as the temperature increasing from 30 to 60oC, whereas the allowed indirect electronic transition energy gap increase from 2.02 up to 2.17 eV as the temperature increase from 30 to 60oC. The effect of temperature on the optical properties such as Urbach’s energy, Refractive index, Extinction coefficient, Critical angle, Brewster angle, and Finesse coefficient of PS doped with DCM thin films also studied in this work.

Revealing the Phenomena of Heat and Photon Energy on Dealing Matter at Atomic level

Technology is in the way to reach in its climax but the basic understanding of science in many phenomena is still awaited despite the fact that nature justifies all those. Scientific research reveals strong analogy between electron and photon. Atoms that execute suitable electronic transitions, on absorbing heat energy at shunt level, excite their electrons. De-excitation of an electron under the gravitational force of its nucleus, where inertia is involved, results into depicting energy in the shape like Gaussian distribution. The wavelength of photon remains in inter-state electron&rsquo;s gap where the source of generating energy in wave-like fashion is due to confined electron-dynamics of that atom eligible to execute electronic transition; energy configures under electron&rsquo;s trajectory while excitation period is due to inertia-levitation-inertia behaviours and energy configures under electron&rsquo;s trajectory while de-excitation period is due to inertia-gravitation-inertia behaviours. Silicon atom is a model system of it. Uninterrupted confined inter-state electron&rsquo;s motion results into configure force energy that can travel immeasurable length where interruption from the point of generation termed it a photon. Such photons increase wavelength under decreasing energy. Here, I discuss that heat energy is due to merged photons or squeezed photons and photonic current is due to the configuring energy in inter-state electron&rsquo;s gap under confined electron-dynamics of the atom. Force of repulsion or attraction in certain materials engages the phenomenon of levitism or gravitism where inertia is exempted. Structural motifs and dynamics are subjected to characteristic photons as long as atoms are dealing neutral behavior of field forces. A structural design delivers straight-forward application on dealing photons of certain wavelengths. Here, heat energy and photon energy explore matter at electron level. Thus, devise science to describe.

Revealing the Phenomena of Heat and Photon Energy on Dealing Matter at Atomic level

Technology is in the way to reach in its climax but the basic understanding of science in many phenomena is still awaited despite the fact that nature justifies all those. Scientific research reveals strong analogy between electron and photon. Atoms that execute suitable electronic transitions, on absorbing heat energy at shunt level, excite their electrons. De-excitation of an electron under the gravitational force of its nucleus, where inertia is involved, results into depicting energy in the shape like Gaussian distribution. The wavelength of photon remains in inter-state electron&rsquo;s gap where the source of generating energy in wave-like fashion is due to confined electron-dynamics of that atom eligible to execute electronic transition; energy configures under electron&rsquo;s trajectory while excitation period is due to inertia-levitation-inertia behaviours and energy configures under electron&rsquo;s trajectory while de-excitation period is due to inertia-gravitation-inertia behaviours. Silicon atom is a model system of it. Uninterrupted confined inter-state electron&rsquo;s motion results into configure force energy that can travel immeasurable length where interruption from the point of generation termed it a photon. Such photons increase wavelength under decreasing energy. Here, I discuss that heat energy is due to merged photons or squeezed photons and photonic current is due to the configuring energy in inter-state electron&rsquo;s gap under confined electron-dynamics of the atom. Force of repulsion or attraction in certain materials engages the phenomenon of levitism or gravitism where inertia is exempted. Structural motifs and dynamics are subjected to characteristic photons as long as atoms are dealing neutral behavior of field forces. A structural design delivers straight-forward application on dealing photons of certain wavelengths. Here, heat energy and photon energy explore matter at electron level. Thus, devise science to describe.