This book gives an overview on the fundamentals and recent developments in the field of luminescent materials. Starting from the definitions and properties of phosphors, novel application areas as ...well as spectroscopic methods for characterization will be described. The reader will benefit from the vast knowledge of the authors with backgrounds in industry as well as academia.
In this study, we developed two novel sky blue fluorescent fluorophores comprising ethyl alcohol (
FOH
) and ethanethiol (
FSH
) units appended to fluoranthene at the periphery. Single Crystal X-Ray ...Diffraction (SC-XRD) studies reveal that the molecular flexibility of alkyl chains leads to distinct diagonal (
FOH
) and ladder (
FSH
) shaped supramolecular arrangements in the crystal lattices. Detailed photophysical and DFT studies showed that
FOH
and
FSH
demonstrate high sensitivity and selectivity towards the detection of trinitrophenol (TNP).
FSH
exhibits high quenching efficiency (∼84%), a rate constant of
K
SV
= 1.1 × 10
4
M
−1
with a limit of detection of ∼97 ppm in THF, and ∼76 ppm in river water. Mechanistic investigation through NMR and SC-XRD of the
FSH
adduct with 1,3-dinitrobenzene (DNB) reveal strong π-π interactions (3.518 Å). Furthermore, photoinduced electron transfer occurs from the fluorophores to the nitro analytes and leads to strong intermolecular interactions using the static quenching mechanism. Both fluorophores were employed in advanced surveillance to identify finger marks on a wide range of substrates (glass, cellophane tape, aluminium foil and floor tiles) with different resolutions to provide an unadorned and lucrative method for viewing the latent fingerprints (LFPs) with exceptionally consistent evidence of up to level 3 and without the requirement for post-treatments, leading to promising applications for onsite forensic analysis. Furthermore,
FOH
and
FSH
were evaluated in 72 hpf zebrafish larvae/embryos to demonstrate the non-toxicological behaviour and fluorescence imaging/tracking.
Two novel fluoranthene ensembles with ethyl alcohol (FOH) and ethanethiol (FSH) functionality with distinct diagonal and ladder arrangements in the crystal lattices were developed for Latent Fingerprints (LFPs) towards analysis of explosives.
The design of portable devices by immobilization of sensory probes using donor–acceptor (D–A) architectures enables the visual detection and onsite analysis of volatile organic compounds (VOCs). In ...this work, we have reported on the synthesis of different D–A architectures of 2-thiohydantoin (2TH) derivatives by extending the conjugation with phenyl (Ph-2TH), naphthalene (Naptha-2TH), and anthracene (Anthra-2TH) moieties at the C5 position. Single-crystal X-ray analysis reveals that extending the conjugation leads to variation in the molecular arrangement in the crystal lattice. Ph-2TH and Naptha-2TH show ribbon-like self-assembled layered arrangements, whereas Anthra-2TH crystallized in herringbone packing in the crystal lattice. The C–S···H interactions were varied with interatomic distances of 2.67, 2.63, and 2.27 Å, respectively, for phenyl, naphthalene, and anthracene. The photophysical and excited-state gas-phase interactions using scanning kelvin probe studies reveal that 2TH ensembles alter their surface photovoltages toward recognition of different VOCs (like ethanol, acetone, toluene, triethylamine, nonanal, and chloroform) depending on their donor and acceptor nature. All three 2TH derivatives showed n-type behavior with high selectivity toward nonanal, and Anthra-2TH exhibited high response (91.02%) within 278 s as well as recovery (92.83%) in surface photovoltages in 647 s. Combined experimental and computational studies demonstrate that the aromatic moieties appended 2TH ensembles would be an efficient D–A ensemble for the detection of VOCs containing carbonyl and alcohol functionalities aiding strong intermolecular interactions.
•Development metalloporphyrins doped PMMA polymer thin films.•Study of dielectric parameters as function of temperature and frequency.•CuTPPOH4 exhibits high conductivity while NiTPPOH4 show ...insulating behaviour.•Variation of conductivity was studied by quantum tunnelling model.
The present work reports on the dielectric behaviour of two different metallo porphyrins (NiTPPOH4 and CuTPPOH4) doped in poly (methyl methacrylate) (PMMA) polymer matrix. Different dielectric parameters such as dielectric constant, tangent loss and a.c. conductivity were measured at frequency ranges from 1- 100 kHz in the temperature range 35–100 °C. The dielectric constant ε' for NiTPPOH4 and CuTPPOH4 was found to be in the range of 2.42–5.45 and dielectric loss (tan δ) in the range of 0.0122–0.0756. The dielectric constant and loss are found to be higher for CuTPPOH4. Variation in the dielectric loss with temperature at different frequencies show a shoulder peak indicating dipolar relaxation character. The a.c. conductivity of the materials increased with temperature and frequency. The activation energy was decreased with rise in temperature and shifting of relaxation regions towards low temperature is observed. Detailed analysis reveal that CuTPPOH4 doped polymer exhibit significant dielectric properties.
Anion recognition and sensing via artificial receptors have attracted a great deal of attention due to their significant role in chemical, biological, medical, and environmental applications. In the ...present investigation, we have demonstrated facile and straightforward synthesis of three low molecular weight fluorophore molecules designated as 2,7 - dihydrobenzo 1,2,3 - cd:4,5,6-c'd'bis(indazole) DHBBI, 2-(benzo1,2,3-cd:4,5,6-c'd'bis(indazole)-2(7H)-yl)ethanol DHBBI-OH and 2-(benzo1,2,3-cd:4,5,6-c'd'bis(indazole)-2(7H)-yl)ethyl methacrylate DHBBI-MA for the fluorometric detection of fluoride and thiocyanate ions in solution phase. DHBBI was synthesized by a condensation reaction of 1,5-dichloroanthraquinone with hydrazine monohydrate. DHBBI-OH was synthesized by the reaction of DHBBI with 2-bromoethanol using K2CO3 as base whereas, DHBBI-MA was synthesized by the reaction of DHBBI-OH with methacrylic anhydride using dimethylamino pyridine (DMAP). Novel three molecules were characterized by 1H NMR, FT-IR, HR-MS and UV–Vis spectroscopy. The strong fluorescence nature of the compounds was further analyzed towards the detection of different ions. All the compounds DHBBI, DHBBI-OH, and DHBBI-MA showed turn on fluorescence behavior for fluoride (F-) ion and turn off fluorescence behavior for thiocyanate (SCN-) ion respectively.
PbO–Sb2O3–B2O3 glasses mixed with different concentrations of Pr2O3 (ranging from 0 to 0.6 mol%) were crystallized. The samples were characterized by X‐ray diffraction (XRD) and transmission electron ...microscopy techniques. The XRD studies have revealed the presence of Pb5Sb2O8, Pb3(SbO4)2, PbB4O7, β‐PrSbO4, Pr3SbO7, and Pr3Sb5O12 crystalline phases. Optical absorption (in the visible and NIR regions) and fluorescence spectra of these samples have been recorded at room temperature. The Judd–Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of Pr3+ ions in these samples. From the luminescence spectra, various radiative properties like transition probability A, branching ratio βr, and the radiative lifetime τr for various emission levels originating from the 3P0 level of Pr3+ ion in the glasses glass ceramic samples have been evaluated. The radiative lifetime of the 3P0→3H6 transition is measured and the quantum efficiency has been estimated. The crystallization causes to improve the luminescence efficiency to a large extent. The changes observed in the radiative properties due to crystallization have been discussed in the light of varying co‐ordinations of antimony ions in the glass network.
Gas sensing properties of diverse phthalocyanines functionalized TiO2/ZnO heterojunction thin films were investigated respect to a number of volatile organic compounds (VOCs) in both dark and light ...conditions. These studies showed that influence of heterojunction along with functionalization alter the optical properties and gas sensing of sensors. Results show that each sensor exhibits a different pattern of relative sensitivity, and this feature can be used to discriminate among a wide range of VOCs.
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