Plant non-specific lipid-transfer proteins (nsLTPs) are small, basic proteins present in abundance in higher plants. They are involved in key processes of plant cytology, such as the stablization of membranes, cell wall organization, and signal transduction. nsLTPs are also known to play important roles in resistance to biotic and abiotic stress, and in plant growth and development, such as sexual reproduction, seed development and germination. The structures of plant nsLTPs contain an eight-cysteine residue conserved motif, linked by four disulfide bonds, and an internal hydrophobic cavity, which comprises the lipid-binding site. This structure endows stability and increases the ability to bind and/or carry hydrophobic molecules. There is growing interest in nsLTPs, due to their critical roles, resulting in the need for a comprehensive review of their form and function. Relevant topics include: nsLTP structure and biochemical features, their classification, identification, and characterization across species, sub-cellular localization, lipid binding and transfer ability, expression profiling, functionality, and evolution. We present advances, as well as limitations and trends, relating to the different topics of the nsLTP gene family. This review collates a large body of research pertaining to the role of nsLTPs across the plant kingdom, which has been integrated as an in depth functional analysis of this group of proteins as a whole, and their activities across multiple biochemical pathways, based on a large number of reports. This review will enhance our understanding of nsLTP activity in planta, prompting further work and insights into the roles of this multifaceted protein family in plants.

A platinum 2,2 0 -bipyridine complex (1) bearing 2-(benzothiazol-2 0 -yl)-9,9-diethyl-7-ethynylfluorene ligands was synthesized and characterized. Its photophysical properties and nonlinear absorption characteristics were systematically investigated by UV-vis absorption, emission, and transient difference absorption spectroscopy, as well as Z-scan and nonlinear transmission techniques. Complex 1 exhibits a strong structureless 1 π,π* absorption band at 374 nm and a broad, weak metalto-ligand charge transfer ( 1 MLCT) transition in the visible region in CH 2 Cl 2 solution. It emits at approximately 565 nm with vibronic structures at room temperature in polar solvents, attributed to the acetylide ligand 3 π,π* excited state. In low-polarity solvents such as hexane and toluene, the emission band becomes structureless and red-shifted, which is assigned to the 3 MLCT state. The emission spectrum becomes more structured and slightly blue-shifted at 77 K in butyronitrile glassy matrix. In femtosecond and nanosecond transient absorption measurements, 1 exhibits both singlet and triplet excited-state absorption from 450 to 800 nm, which are tentatively attributed to the 1 π,π*/ 1 MLCT and 3 π,π*/ 3 MLCT, respectively. Z scan experiments were carried out using nanosecond and picosecond pulses at 532 nm, and picosecond pulses at a variety of other wavelengths in the visible and near-IR, and the experimental data were fitted by a five-level model using the excited-state lifetimes and estimated cross-section values from the photophysical study. In this way, values were obtained for the first and second singlet excited-state absorption cross sections and the triplet excitedstate absorption cross section throughout the visible and near-IR and for the two-photon absorption (TPA) cross section in the near-IR region. Our results demonstrate that 1 possesses extremely large ratios of the excited-state absorption cross sections to the ground-state absorption in the visible spectral region and, compared to the other two-photon absorbing platinum complexes, the largest two-photon absorption cross sections in the near-IR region. This makes complex 1 a very promising candidate for photonic devices that require large and broadband nonlinear absorption. Reverse saturable absorption of 1 in CH 2 Cl 2 solution at 532 nm for a nanosecond laser pulse was demonstrated. A remarkable transmission decrease was observed when the incident fluence increased.

A series of platinum 4,6-diphenyl-2,2'-bipyridine complexes (6-10) with alkoxyl substituent on the 6-phenyl ring have been synthesized and characterized. The influence of the alkoxyl substituent on the nature of the low-lying excited states, and thus the photophysical properties, have been systematically investigated spectroscopically and theoretically. Complexes 6-10 exhibit a broad low-energy charge-transfer absorption band from 400 to 500 nm, which shows weak negative solvatochromic effect. They all emit at about 590 nm in fluid solutions at room temperature, with the emission energy essentially independent of the nature of the monodentate ligand and the polarity of solvent. The excited-state lifetimes of 6 and 7 are much longer (approximately 460-570 ns) than those of their corresponding "alkoxyl free" analogues 12 and 13 (approximately 40-100 ns) in CH(3)CN. Additionally, the emission quantum yields of 7-9 in CH(2)Cl(2) are quite high (0.15-0.21). Spectroscopic studies and Time-Dependent Density Functional Theory (TDDFT) calculations indicate that these unique photophysical properties are induced by the electron-donating ability of the alkoxyl substituent, which causes a mixture of the intraligand charge transfer (ILCT) with the metal-to-ligand charge transfer (MLCT)/ligand-to-ligand charge transfer (LLCT) in their low-lying excited states. Complexes 6-10 exhibit broad triplet transient difference absorption in the near-UV to the near-IR region, where reverse saturable absorption (RSA) could occur. Nonlinear absorption experiments at 532 nm for nanosecond laser pulses demonstrate that 6-9 are strong reverse saturable absorbers, while 10 exhibits weak RSA because of its larger ground-state absorption cross-section and its low triplet excited-state quantum yield.