ABSTRACT
Naphthalimide derivatives composed of donor-acceptor type structures hold significant promise across a wide range of applications. Here, the solvent polarity and viscosity controlled excited-state dynamics of a naphthalimide derivative with a donor-acceptor structure were studied using multiple spectroscopic techniques. From the stationary spectroscopic investigations, large Stokes shift and low fluorescence quantum yield were observed with increasing the solvent polarity, suggesting a more polar excited state relative to the ground state, which is evidenced by the Lippert-Mataga relationship. We also observe an enhanced fluorescence with a prolonged lifetime in a more viscous solution due to the restriction of excited-state molecular rearrangement. These observations result from the emerged twisted intramolecular charge transfer (TICT) state. The ultrafast spectroscopy studies further unravel a solvent polarity dependent excited state evolution from the intramolecular charge transfer state to the TICT state, revealing that the TICT state can be populated only in strong polar solvents. Control experiments by tuning the solvent viscosity in ultrafast experiments were employed to verify the excited state molecular rearrangement subsequently. These observations collectively emphasize how fine-tuning the photophysical properties of naphthalimide derivatives can be achieved through strategic manipulation of solvent polarity and viscosity.
ABSTRACT
Bright and colorful fluorescent polymers are ideal materials for a variety of applications. Although polymers could be made fluorescent by physical doping or chemical binding of fluorescent units, it is a great challenge to get colorful and highly emissive polymers with a single fluorophore. Here the development of a general and facile method to synthesize ultrabright and colorful polymers using a single twisted intramolecular charge transfer (TICT) probe is reported. By incorporating polymerizable, highly fluorescent, and environmental sensitive TICT probe, a series of colorful acrylic polymers (emission from 481 to 543 nm) with almost 100% fluorescence quantum yields are prepared. Like the solvatochromic effect, functional groups within side chains of acrylic polymers (including alkyl chain, tetrahydrofurfuryl group, and hydroxyl group) provide varied environmental polarity for the incorporated fluorophore, resulting in a series of colorful polymeric materials. Benefiting from the excellent photophysical properties, the polymers show great potential in encryption, cultural relics protection, white light-emitting diode bulb making, and fingerprint identification.
Subject(s)
Fluorescent Dyes , Polymers , Fluorescence , Fluorescent Dyes/chemistryABSTRACT
ZnO seed layers were deposited on silicon and sapphire substrates by the pulsed laser deposition (PLD) method, and ZnO nanorod arrays with different orientation degrees were grown using the chemical vapor deposition (CVD) method. Flat-type gas sensors based on the ZnO nanorod arrays were fabricated, and their gas sensitivity properties were studied. The ZnO seed layer with a thickness of approximately 450 nm exhibits high c-axis orientation and possesses few defects. The ZnO nanorods fabricated on both of the substrates grow along the [0001] direction and contain a large number of oxygen vacancy defects. These nanorods have lengths of 8~10 µm and diameters of 200~500 nm. The ZnO nanorods grown on the silicon substrate are perpendicular to the surface of the substrate, and their areal density is approximately 3.0×108/cm², while those grown on the sapphire substrate exhibit a lower orientation degree, and their areal density is approximately 0.9×108/cm². The largest response of the gas sensor for gaseous alcohol reaches 48.2, and the optimal operating temperature for all of the sensors is approximately 280 °C. The gas sensitivity property of the silicon-based sensor is superior to that of the sapphire-based sensor, and the corresponding sensing mechanism is discussed.
ABSTRACT
A total of 39 Y-chromosomal short tandem repeat (Y-STR) loci included in the advanced commercial six-dye multiplex system (AGCU Database Y30 kit) and a custom-designed four-dye multiplex system were investigated in 259 unrelated healthy Chinese males residing in Henan Province, central China. The haplotype diversity (HD) values were 0.99997 and 1.0000 for the six and four fluorescent-multiplex amplification systems, respectively. The discrimination capacity (DC) values were 0.9961 and 1.0000, respectively. When the 39 Y-STR loci were considered, 259 unique haplotypes were obtained in Henan Han individuals with both the haplotype diversity and discrimination capacity being 1.000. The gene diversity (GD) of 39 Y-STR loci in the studied group ranged from 0.3956 (DYS588) to 0.9990 (DYF403S1). Population comparisons between the Henan Han and 24 reference groups were performed. Both multidimensional scaling plots and phylogenetic analysis demonstrated that significant genetic differences existed between Henan Han and reference ethnic minorities of China, particularly the Tibetan, Uighur, and Mongolian populations. Moreover, the results indicated that 39 Y-STRs included in the two fluorescent-multiplex amplification systems are highly polymorphic and informative in the studied populations and can be employed as complementary tools for forensic application and human genetics research.
