Room-temperature phosphorescent materials that emit light in the visible (red, green, and blue; from 400 to 700 nm) have been a major focus of research and development during the past decades, due to their applications in organic light-emitting diodes (OLEDs), light-emitting electrochemical cells, photovoltaic cells, chemical sensors, and bio-imaging. In recent years, near-infrared (NIR) phosphorescence beyond the visible region (700-2500 nm) has emerged as a new, promising, and challenging research field with potential applications toward NIR OLEDs, telecommunications, night vision-readable displays. Moreover, NIR phosphorescence holds promise for in vivo imaging, because cells and tissues exhibit little absorption and auto-fluorescence in this spectral region. This review describes the overall progress made in the past ten years on NIR phosphorescent transition-metal complexes including Cu(I), Cu(II), Cr(III), Re(I), Re(III), Ru(II), Os(II), Ir(III), Pt(II), Pd(II), Au(I), and Au(III) complexes, with a primary focus on material design complemented with a selection of optical, electronic, sensory, and biologic applications. A critical comparison of various NIR phosphorescent materials reported in the literature and a blueprint for future development in this field are also provided.

A laboratory experiment visually exploring two opposite basic principles of fluorescence of aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) is demonstrated. The students would prepared two salicylaldehyde-based Schiff bases through a simple one-pot condensation reaction of one equiv of 1,2-diamine with 2 equiv of salicylaldehyde. The resulting fluorescent dyes have similar chemical structures but possess ACQ and AIE properties, respectively. Their ACQ/AIE properties and pH sensing applications would then examined by visually qualitative analysis (UV lamp, light-emitting diode, and naked eye) and quantitative analysis (fluorometer). Finally, in a deeper level, X-ray single crystal structure analysis was utilized to reveal the inherent relationships between molecular structures/molecular arrangements and ACQ/AIE properties. This lesson is suitable for many areas of chemistry, especially for organic and analytical chemistry.

The quantitative determination of oxygen concentration is essential for a variety of applications ranging from life sciences to environmental sciences. Optical oxygen sensing allows non-invasive measurements with biological objects, parallel monitoring of multiple samples, and imaging. In general, ratiometric optical oxygen sensing is more desirable, due to its advantages of selectivity, insensitivity to ambient or scattered light, and elimination of instrumental fluctuation. Moreover, it can provide the perceived colour change, which would be useful not only for the ratiometric method of detection but also for rapid visual sensing. Mainly focusing on material design for ratiometric measurement, this review describes the overall progress made in the past ten years on ratiometric optical ground-state triplet oxygen sensing and offers a critical comparison of various methods reported in the literature. It also provides a development blueprint for ratiometric optical oxygen sensing.

We report our systematic studies of novel, simple, selective, and sensitive optical (both colorimetric and fluorescent) chemosensors for detecting Al(3+) based on transmetalation reactions (metal displacement or exchange reactions) of a series of K(I), Ca(II), Zn(II), Cu(II), and Pt(II) complexes containing different ligands of salen-based Schiff bases. Both the chemical structure of the salen ligand and the identity of the central metal ion have a tremendous impact on the sensing performance, which is mainly determined by the stability constant of the complex. Moreover, the selectivities of the salen-complex-based chemosensors are much better than those of the corresponding free salen ligands because of the shielding function of the filled-in metal ion in the complex. Therefore, the present work potentially provides a new and simple way to design optical probes via complex-based transmetalation reactions.

Organic field-effect transistors incorporating planar pi-conjugated metal-free macrocycles and their metal derivatives are fabricated by vacuum deposition. The crystal structures of [H2(OX)] (H(2)OX=etioporphyrin-I), [Cu(OX)], [Pt(OX)], and [Pt(TBP)] (H2TBP=tetra-(n-butyl)porphyrin) as determined by single crystal X-ray diffraction (XRD), reveal the absence of occluded solvent molecules. The field-effect transistors (FETs) made from thin films of all these metal-free macrocycles and their metal derivatives show a p-type semiconductor behavior with a charge mobility (mu) ranging from 10(-6) to 10(-1) cm(2) V(-1) s(-1). Annealing the as-deposited Pt(OX) film leads to the formation of a polycrystalline film that exhibits excellent overall charge transport properties with a charge mobility of up to 3.2 x 10(-1) cm(2) V(-1) s(-1), which is the best value reported for a metalloporphyrin. Compared with their metal derivatives, the field-effect transistors made from thin films of metal-free macrocycles (except tetra-(n-propyl)porphycene) have significantly lower mu values (3.0 x 10(-6)-3.7 x 10(-5) cm(2) V(-1) s(-1)).