Dual and Panchromatic Emission from -Aryl-phenanthridinones: Extension of the Seesaw Photophysical Model with a Slight Twist.

White-light emission from a single organic molecule, known as a single white-light emitter, is a rare phenomenon and desirable property for a class of materials with potential future applications in white lighting. Since -aryl-naphthalimides (NANs) have been shown to follow excited state behavior and unique dual or panchromatic emission through a substituent pattern prescribed via a seesaw photophysical model, this study investigates the substituent effects on the fluorescence emission of structurally related -aryl-phenanthridinones (NAPs) dyes. Following a similar placement prescription of an electron-releasing group (ERG) and electron-withdrawing group (EWG) at the phenanthridinone core and -aryl moiety, we discovered from time-dependent density functional theory (TD-DFT) results that NAPs show a substitution pattern opposite to NANs in order to promote S and higher excited states.

Photons to Formate-A Review on Photocatalytic Reduction of CO to Formic Acid.

Rising levels of atmospheric carbon dioxide due to the burning and depletion of fossil fuels is continuously raising environmental concerns about global warming and the future of our energy supply. Renewable energy, especially better utilization of solar energy, is a promising method for CO conversion and chemical storage. Research in the solar fuels area is focused on designing novel catalysts and developing new conversion pathways.

Electronic Properties and Electroluminescent OLED Performance of Panchromatic Emissive N-Aryl-2,3-naphthalimides.

This report investigates the excited-state properties of a series of N-aryl-2,3-naphthalimides along with their fabrication into OLEDs and electroluminescence measurements. The N-aryl-2,3-NIs substituted specifically with chloro, fluoro, and methoxy substituents were chosen because of their unique propensity to display two emission bands or panchromatic fluorescence. Using the Lippert-Mataga analysis along with TD-DFT calculations, the excited states were determined to be n,π* and π,π*.

Selective Modulation of Internal Charge Transfer and Photoinduced Electron Transfer Processes in N-Aryl-1,8-Naphthalimide Derivatives: Applications in Reaction-Based Fluorogenic Sensing of Sulfide.

Three reaction-based fluorescent probes based on two new naphthalimide platforms were developed for the detection of HS. A new approach in detecting HS by the reduction of an azide to a triazene intermediate in aqueous media is reported. Given their design features, these chemodosimeters provide useful insights into the relatively unexplored area of C spacers between receptor:reporter components.

Photocatalyzed Reduction of Bicarbonate to Formate: Effect of ZnS Crystal Structure and Positive Hole Scavenger.

Zinc sulfide is a promising catalyst due to its abundance, low cost, low toxicity and conduction band position that enables the photoreduction of CO2 to formic acid. This study is the first to examine experimentally the photocatalytic differences between wurtzite and sphalerite under the parameters of size (micrometer and nanoscale), crystal lattice, surface area, and band gap on productivity in the photoreduction of HCO3(-). These photochemical experiments were conducted under air mass coefficient zero (AM 0) and AM 1.

An abiotic fluorescent probe for cardiac troponin I.

The first ratiometric fluorescent reporter was designed for the detection of cardiac troponin I (cTnI), a key protein elicited during cardiac muscle cell death. In designing this abiotic fluorescent probe, docking simulation studies were performed to predict the probe/protein interactions along the solvent exposed regions of cTnI. Simple cuvette titration experiments in aqueous buffered solution indicate remarkable selectivity for cardiac troponin in the clinically relevant nM region versus skeletal troponin.

Dual fluorescent N-aryl-2,3- naphthalimides: applications in ratiometric DNA detection and white organic light-emitting devices.

A ten element matrix of 5- and 6-substituted-(2,3)-naphthalimides was prepared for the appropriate placement of substituents necessary to promote dual fluorescence (DF). As prescribed by our balanced seesaw photophysical model this matrix yielded nine new DF dyes out of a possible ten compounds. From this set of nine DF dyes, 4-fluoronaphthalic amide (37) was selected as a probe for ratiometric detection of DNA and demonstration of panchromatic emission.

An organic white light-emitting dye: very small molecular architecture displays panchromatic emission.

The synthesis and photophysical characterization of a new white-light fluorophore is described. The optimization of excitation wavelengths allows the naphthalimide (NI) dyes to display blue, green or white light emission depending on the excitation wavelength.

Frontier molecular orbital analysis of dual fluorescent dyes: predicting two-color emission in N-aryl-1,8-naphthalimides.

A 3 x 3 matrix of disubstituted N-aryl-1,8-naphthalimides was synthesized for the evaluation and discovery of dual fluorescence (DF). The matrix elements included for this study were based on a predictive model that is proposed as a seesaw balanced photophysical model. This model serves as a guide to optimize the dual fluorescence emission from N-phenyl-1,8-naphthalimides by appropriate placement of substituent groups at both the 4-position of the N-arene as well as the 4'-position of the naphthalene ring.

Discovery of dual fluorescent 1,8-naphthalimide dyes based on balanced seesaw photophysical model.

The 3 x 3 matrix elements included for the evaluation of dual fluorescence are based on a predictive model described as a 'seesaw balanced' photophysical model.

Highly water-soluble monoboronic acid probes that show optical sensitivity to glucose based on 4-sulfo-1,8-naphthalic anhydride.

Two highly water-soluble monoboronic acid probes that display the more desirable off-on fluorescence response were synthesized based on 4-sulfo-1,8-naphthalic anhydride and a remarkable sensitivity for glucose rather than fructose and galactose was also observed.

A comparative study into two dual fluorescent mechanisms via positional isomers of N-hydroxyarene-1,8-naphthalimides.

Three isomers of hydroxy substituted N-aryl-1, 8-naphthalimides based on N-aryl naphthalic anhydride fluorophore have been synthesized. The decrease in fluorescence intensity from ortho to para substitution of hydroxy group on N-aryl reveals that para substituted isomer undergoes ESEC (Excited State with Extended Conjugation) mechanism which is proved by low quantum yield and appearance of dual emission. The ortho isomer, however, has high quantum yield and no tautomer emission, indicating ESIPT (Excited State Intramolecular Proton Transfer) mechanism is not operating.

Toward intrinsically fluorescent proteomimetics: fluorescent probe response to alpha helix structure of poly-gamma-benzyl-L-glutamate.

A fluorescent probe (1), developed for recognition of alpha helical secondary structure, shows a large fluorescence change upon titration with the synthetic protein PBLG. Compared to fluorophores of similar size and shape, 1 displayed the smallest dissociation constant (K(D)=80microM) when titrated with PBLG. These preliminary studies are directed toward developing small molecule proteomimetics that have intrinsic fluorescence and are specific for helical-protein binding-sites.

Matrix screening of substituted N-aryl-1,8-naphthalimides reveals new dual fluorescent dyes and unusually bright pyridine derivatives.

A 3 x 14 matrix of substituted N-aryl-1,8-naphthalimides was synthesized for the evaluation and discovery of dual fluorescence. Because of their unique photophysical properties, these dual fluorescent systems represent an exception to the widely studied TICT (Twisted Internal Charge Transfer) fluorescent dyes or tautomeric benzofluorescein class of two-color dyes. The matrix library was designed to investigate the effects of heterocycles, particularly pi-excessive and pi-deficient systems.

Fluorescent chemosensors for carbohydrates: a decade's worth of bright spies for saccharides in review.

This review provides a chronological survey of over fifty fluorescent chemosensors for carbohydrates from the period between 1992 to the present. The survey contains only those sensors that are synthetic or chemosensory, utilize boronic acids and display a fluorescence response in the form of intensity changes or shifts in wavelength. With each compound listed, a description of the saccharide probe is given with regard to concentration, excitation and emission wavelengths, pH and solvent mixture proportions.

Substituent effects on monoboronic acid sensors for saccharides based on N-phenyl-1,8-naphthalenedicarboximides.

In the course of our investigations on new monoboronic acid saccharide sensors with C(0) spacers, a series of probes 1-6 based on 1,8-naphthalenedicarboximide were synthesized. Sensor 1 displays features typical of PET monoboronic acid sensors and shows high selectivity to fructose. Sensor 2 exhibits a novel dual emission and remarkable sensitivity for glucose relative to fructose and galactose through subtle changes in pH.

Spectroscopic and Photophysical Characterization of Fluorescent Chemosensors for Monosaccharides Based on -Phenylboronic Acid Derivatives of 1,8-Naphthalimide.

Spectroscopic and photophysical properties of two fluorescent probes for monosaccharides are presented. Probes are based on the -phenyl-1,8-naphthalimide structure having the boronic acid group [R-B(OH)] in in one case, and in the other case, positions of the -phenyl group. Formation of the anionic form of the boronic acid group [ ] induced a substantial decrease of the steady-state fluorescence of both compounds.

Monoboronic acid sensor that displays anomalous fluorescence sensitivity to glucose.

[reaction: see text]. A monoboronic acid fluorescent sensor was conveniently synthesized from 3-nitronaphthalic anhydride and 3-aminophenylboronic acid. This novel saccharide probe exhibits dual emission suitable for ratiometric sensing and displays a remarkable sensitivity for glucose relative to fructose and galactose.