Synthesis and Excimer Formation Properties of Electroactive Polyamides Incorporated with 4,5-Diphenoxypyrene Units

A new dietherpyrene-cored diamine monomer, namely, 4,5-bis(4-aminophenoxy)pyrene, was successful synthesized and formed a series of electroactive polyamides with an aryloxy linkage in a polymer main chain and bearing pyrene chromophore as a pendent group using conventional one-pot polycondensation reactions with commercial aromatic/aliphatic dicarboxylic acids. The resulting polyamides exhibited good solubility in polar organic solvents and, further, can be made into transparent films. They had appropriate levels of thermal stability with moderately high glass-transition values. The dilute NMP solutions of these polyamides exhibited pyrene characteristic fluorescence and also showed a remarkable additional excimer emission peak centered at 475 nm. Electrochemical studies of these polymer films showed that these polyamides have both p- and n-dopable states as a result of the formation of radical cations and anions of the electroactive pyrene moieties.

Deep-Red Electro-fluorescent based on an Excimer Emission with Hot-Exciton Channels

Red and deep-red fluorescent materials are broadly applied in many fields such as organic light emitting diodes (OLEDs), biological imaging and night-vision devices. In this work, we designed and synthesized...

Pyrene-based monomer-excimer dual response organosilicon polymer for selective detection of 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP)

The formation or destruction of pyrene excimer with strong emission change make it a versatile fluorophore to construct excimer emission-based fluorescence probes for various analytes detection. The distinct difference between...

Neutral bremsstrahlung and excimer electroluminescence in noble gases and its relevance to two-phase dark matter detectors

Proportional electroluminescence (EL) is the physical effect used in two-phase detectors for dark matter searches, to optically record (in the gas phase) the ionization signal produced by particle scattering in the liquid phase. In our previous work the presence of a new EL mechanism, namely that of neutral bremsstrahlung (NBrS), was demonstrated in two-phase argon detectors both theoretically and experimentally, in addition to the ordinary EL mechanism due to excimer emission. In this work the similar theoretical approach is applied to all noble gases, i.e. overall to helium, neon, argon, krypton and xenon, to calculate the EL yields and spectra both for NBrS and excimer EL. The relevance of the results obtained to the development of two-phase dark matter detectors is discussed.

Optical Investigation of Essential Oils Using Absorbance and Photoluminescence

Essential oils are complex mixtures of organic substances with large commercial importance in the pharmaceutical, food, fragrance, and cosmetic industries due to their organoleptic and biological properties. Also, these materials are also luminescent what has taken several studies about its potential uses for the detection and quality control of essential oils, imaging, and for the investigation of the synergies of their constituents. Concerning this, the present work is dedicated to studying the optical properties of selected essential oils: citronella ( Cymbopogon winterianus), Japanese mint ( Mentha arvensis), clove bud ( Syzygium aromaticum), and bergamot ( Citrus bergamia). We carried out a comparative study of the photoluminescence and the UV–Vis optical absorption (abs-UV–Vis) of these essential oils with their typical constituents. To inspect the effects of the intermolecular interactions on the optical response of these systems, mixtures between the essential oils constituents following the expected average percent mass fraction were also studied. From these experiments, the main results were bathochromic effects in the abs-UV–Vis spectra; excimer formation in citral, isopulegol, isomenthone, eugenol, and eugenyl acetate; excimer emission enhancing and specific solvent effect in the essential oils photoluminescence spectra. These results contribute to the knowledge of essential oils’ applications, especially in the evaluation of components’ interactions through a simple abs-UV–Vis assay.