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Luminescent complexes illustrate high interest as luminescent materials in the fields of optical communications, lighting, sensors and biomedical devices. This review gives the structural and luminescent studies on isonicotinic acid based complexes, and probably provides the structure-property relationship. These complexes display various luminescent properties, such as luminescent probe, different luminescence when immersed in different organic solvents. This review is divided into three sections to discuss, including transition-metal, lanthanide, lanthanide-transition heterometal. The approach will help design and synthesis of luminescent complexes as promising materials.

A novel hexanuclear CoII complex with the formula of {[Co6(μ3-OH)(Hdhbp)4(dhbp)2(piv)3]·5CH3CN} (1, H2dhbp = 6,6′-dihydroxy-2,2′bipyridine, Hpiv = pivalic acid) was obtained and characterized. Single-crystal X-ray analysis shows that complex 1 contains six crystallographic independent CoII ions, which are gathered in the shell to form a [Co6] cluster. The six CoII ions embrace two coordination environments: the distorted octahedron and the vacant octahedron. Magnetic susceptibility of complex 1 was measured and studied.

Two novel heterometallic complexes with formula of {[Co 2 (HTRI) 3 (H 2 O) 6 ][Dy 2 Co(HCAM) 6 (H 2 O) 4 ]·22H 2 O} ( 1 , H 3 CAM = 4-hydroxyl-2,6-pyridicarboxylic acid; HTRI = 1,2,4-triazole) and {[Dy 2 Co 3 (HTRI) 2 (HCAM) 6 (H 2 O) 10 ]·2CH 3 OH·13H 2 O} n ( 2 ) have been obtained. Single-crystal X-ray diffraction analyses reveal that complexes 1 and 2 show similar molecular elements, but display different structural features: a discrete ionic-pair for complex 1 and an infinite 1D chain for complex 2 , which is probably due to the different coordination modes of HTRI. Luminescent properties have been studied for complexes 1 and 2 , and show the characteristic fluorescence of Dy(III) ions.

Abstrac t The rapidly growing number of luminescent compounds based on lanthanide ions illustrates high interest due to the numerous applications on lighting, optical communications, sensors, photonics and biomedical devices. In this review, we choose luminescent compounds based on pyridine-2,6-dicarboxylic acid to discuss the synthetic strategy of functional luminescent compounds, various types of emitting, tunable emission colors, and the mechanism of enhancing and quenching fluorescence. The unique luminescence features them as promising materials. We focus on recent significant advances of this field and provide a comprehensive review on multifunctional lanthanide compounds.

PM2.5 samples were collected from five different cooking activities, namely, meat roasting, cafeteria frying, fish roasting, snack-street boiling, and cafeteria boiling in Ya’an, China. Their chemical compositions were investigated. The PM2.5 concentrations in the cooking samples were 2.5–9.6 times higher than those in the corresponding backgrounds. Meat roasting produced the highest amount of PM2.5. In general, charbroilings emitted more PM2.5 than the other cooking activities because of the characteristics of cooking method and fuel type. High organic carbon (OC) contents (> 53% of PM2.5) and OC/EC ratios (> 54) in meat roasting and cafeteria frying samples suggest that oils and high-fat raw materials significantly affect the PM2.5 and OC emissions. However, the cooking activity was proved to be a minor source for elemental carbon (EC) with its low contents in all of the samples. High ion compositions in PM2.5 and WSOC/OC ratios in the snack-street boiling and cafeteria boiling samples represent that water-based cooking emitted more water-soluble species. Considering that high OC/EC ratios were measured in the oil-based cooking samples and most secondary organic aerosols (SOAs) are water soluble, it is more reasonable to estimate SOA with WSOC/OC ratio in populated urban areas. We found that the formation of SOA is significant when the WSOC/OC ratio is larger than 0.40. Principal component analysis (PCA) with the quantified metals identified four contributors to the samples, including coal combustion and non-licensed business activities, soil dust, charcoal burning, and stainless steel utensils, and explained 73% of the total variance. The high emissions of PM2.5 and toxic components from the cooking activities suggest that food safety control and environmental standard establishment should be strengthened in small and medium-sized cities in China.

Two new polynuclear d-metal clusters based on pentaerythritol (H4L), [Mn12] (1) and [Mn10Cd2] (2) for short, were obtained from the reaction of H4L, transition-metal salt and pivalic acid (Hpiv) in the mixed solvent under ambient conditions. Compound 1 crystallizes in the triclinic space group P 1 ¯ , and consists of a dodecanuclear mixed-valent [MnIII4MnII8] cluster. When Cd(NO3)2·4H2O was introduced into the reaction, compound 2 was resulted in, which displays the similar structural feature as compound 1, fabricating a dodecanuclear heterometallic [MnIII4MnII6CdII2] cluster, but crystallizes in the monoclinic space group P21/c. Interestingly, there are two μ5-O bridges present in this structure, and it is rare. Magnetic susceptibilities of compounds 1 and 2 were measured, and antiferromagnetic interactions between metal centers were observed.

A series of lanthanide coordination polymers (Ln-CPs), with the formula of {[Ln(L)3(CH3OH)(H2O)]n} (Ln = Sm (1), Eu (2), HL = 2-chloroisonicotinic acid) and {[Ln(L)3(H2O)2]n} (Ln = Dy (3), Tb (4)), were synthesized under solvothermal condition. This series display two different 1D chains due to the lanthanide contraction: complexes 1 and 2, based on light Sm and Eu, respectively, consist of paddle-wheel [Ln2(COO)4] dimmers through double μ2-COO bridges, and complexes 3 and 4 with heavy Dy and Tb, respectively, show 1D [Ln(COO)2]n chains. The luminescent measurements indicate the typical emissions of corresponding Ln3+ ions in complexes 1–4. Furthermore, complexes 2 and 4 display significant luminescent response for Fe3+ ions with high quenching constant. The result indicates that complexes 2 and 4 can act as luminescent probes for Fe3+ ions with relatively high sensitivity and selectivity.

A pentanuclear {Cr2Gd3} cluster (1) and its diamagnetic substituent-{Al2Gd3} (2) based on pivalic acid (Hpiv) were obtained with the formulas of {Et3NH[M2Gd3(OH)6(piv)10(H2O)2]} (M = CrIII, 1; AlIII, 2). The metallic core shows a triangle bipyramid-{Cr2Gd3} held together by six µ3-OH groups, and the piv- ligands located at the periphery. Magnetic studies for complex 1 exhibit dominant ferromagnetic interactions between CrIII and GdIII ions. Furthermore, ferromagnetic {Cr2Gd3} cluster (1) displays a considerable large magnetic entropy value (−ΔSm = 27.0 J kg−1 K−1) at high temperature among low-nuclearity 3d-4f clusters.

PM2.5 samples were collected at six general stations and one roadside station in Hong Kong in two periods of high particulate matter (PM) in 2003 (27 October–4 November and 30 November–13 December). The highest PM2.5 reached 216 μg m− 3 during the first high PM period and 113 μg m− 3 during the second high PM period. Analysis of synoptic weather conditions identified individual sampling days under dominant influence of one of three types of air masses, that is, local, regional and long‐range transported (LRT) air masses. Roadside samples were discussed separately due to heavy influences from vehicular emissions. This research examines source apportionment of fine organic carbon (OC) and contribution of secondary organic aerosol on high PM days under different synoptic conditions. Six primary OC (POC) sources (vehicle exhaust, biomass burning, cooking, cigarette smoke, vegetative detritus, and coal combustion) were identified on the basis of characteristic organic tracers. Individual POC source contributions were estimated using chemical mass balance model. In the roadside and the local samples, OC was dominated by the primary sources, accounting for more than 74% of OC. In the samples influenced by regional and LRT air masses, secondary OC (SOC), which was approximated to be the difference between the total measured OC and the apportioned POC, contributed more than 54% of fine OC. SOC was highly correlated with water‐soluble organic carbon and sulfate, consistent with its secondary nature.

In this study, we investigate the influence of long-range transport (LRT) episodes brought in by cold front on the concentration levels of PM 2.5 , major aerosol constituents, organic tracers, and PM 2.5 source characteristics in Hong Kong, China. PM 2.5 samples were collected during January–March 2004 and January–March 2005 and analyzed for major constituents and organic tracer species. Synoptic weather conditions and characteristics of common air pollutants were used to categorize the sampling days to three groups, i.e., groups mainly affected by local emissions or regional transport (RT) or cold front LRT. Concentrations of PM 2.5 mass and its major constituents during cold-front days were lower than those during RT-dominated periods but higher than those during local emissions-dominated periods. Source apportionment using chemical mass balance (CMB) indicates that vehicular exhaust was a significant primary OC source of mainly local emissions, making average contributions of 1.82, 1.50, and 2.39 μg C m − 3 to OC in the local, LRT, and RT sample groups, respectively. During cold front periods, primary OC concentrations attributable to biomass burning and coal combustion were approximately triple and double, respectively, those during periods dominated by local emissions. Suspended dust, a minor primary OC source (0.24–0.40 μg C m − 3 ), also showed increased contribution during cold fronts. The unexplained OC by CMB (i.e., total OC minus apportioned primary OC), an approximate indicator for secondary OC, was a significant fraction of OC (> 48%) and its mass concentration was much higher in the cold front LRT and RT sample groups (6.37 and 9.48 μg C m − 3 ) than in the local sample group (3.8 μg C m − 3 ). Source analysis as well as tracer concentration variation shows that biomass burning OC and water soluble organic carbon (WSOC) were correlated, suggesting biomass burning as a significant contributor to WSOC.

PEG-PEI/Fe3O4 nano-magnetic fluids with different mass fractions of reactant were prepared by co-precipitation method. Besides particle size analyzer, the methods of XRD, IR, VSM and AFM were adopted to characterize the synthesized samples. Covalent bonding of PEG, PEI and Fe3O4 exhibits superparamagnetism. The TEM photograph shows that the particles are of stable dispersion and little aggregation, with smooth surface, spherical shape and a diameter of about 80 nm, which meets the requirements of nano-materials. When the mass fraction of PEI in reactant is 25%, the particle size, Zeta-potential and pEGFP-C1 DNA loading efficiency are all satisfactory. In this case, PEG-PEI/Fe3O4 nano-magnetic fluids can be used as gene vectors or targeted drug carriers.