The three new complexes TpPyLn(CH3CO2)2(H2O) (Ln = Eu (1), Gd(2), or Tb (3)) were prepared and characterized crystallographically. In the crystal lattices of these complexes, separate molecules are connected in infinite chains by π-stacking interactions. Complexes 1 and 3 display intense photoluminescence and triboluminescence (red and green respectively), while compound 3 exhibits electroluminescence commencing at 9 V in an ITO/PVK/3/Al device (ITO = indium-tin oxide, PVK = poly(N-vinylcarbazole)). A series of Eu/Tb-doped Gd compounds was prepared by cocrystallization from mixtures of 1 and 2 or 2 and 3, respectively. It was shown that π-stacking interactions are involved in increasing the efficiency of energy transfer from the gadolinium complex to emitting [TpPyEu]2+ or [TpPyTb]2+ centers, and this energy transfer occurs through hundreds of molecules, resembling the process of energy harvesting in chloroplast stacks.

Manifestation of π-π stacking interactions in luminescence properties and energy transfer in aromatically-derived Tb, Eu and Gd tris(pyrazolyl)borate complexes.

Two novel rare earth complexes with curcumin and pyridine have been synthesized and characterized by elemental analysis, FT-IR, 1H-NMR, MS spectroscopy, and thermogravimetric (TG) analysis. The photophysical properties were studied both experimentally and theoretically. The results suggest that the obtained two complexes exhibited obvious two-photon absorption in the range 700–860 nm in DMSO solution, and that presented a significant enhancement of single-/two-photon excited fluorescence and TPA cross section values compared with the free ligand. Additionally, two-photon microscopy fluorescent imaging of MCF-7 cells labeled with the title complexes revealed their potential application as a biological fluorescent probe.

Synthesis, optical properties and biological imaging of the rare earth complexes with curcumin and pyridine

Synthesis, structural, thermal and optical studies of rare earth coordinated complex: Tb(Sal)3Phen

Study of enhanced red emission from Sm(Sal)3Phen ternary complexes in Poly Vinyl Alcohol film

Preparation and photoluminescent properties of europium complexes with methoxy derivatives of 2′-hydroxy-2-phenylacetophenones

Owing to poor flame retardant efficiency and compatibility of traditional flame retardants, it is difficult to prepare unsaturated polyester resins (UPR) composites with excellent flame retardant properties. In this research, novel glycerol-based polymeric flame retardants (PCH3PG, PBPG and POPG) were synthesized. The effect of different side chains, phosphorus contents and combined structures on flame retardancy efficiency of UPR composites were explored. It has been found POPG was more conducive to improving char formation under high temperatures than PCH3PG and PBPG. However, PCH3PG and PBPG exhibited better flame retardant efficiency in flame retaradant UPR composites. Especially for UPR/PCH3PG, the flame retardant performance increased rapidly with increasing PCH3PG contents. With only 15 wt% of PCH3PG in UPR, UPR/PCH3PG 15% reached UL-94 V0 and 29% of LOI. When PCH3PG contents increased to 20 wt%, the LOI of UPR/PCH3PG 20% increased to 30%, and PHRR and THR were reduced by 67.93% and 57.22%, compared with pure UPR. The thermal degradation products and flame retardant mechanism in gaseous and condensed phase were studied. It was found the most efficient PCH3PG was mainly played flame retardant effect in gaseous phase, supplemented by the barrier effect of condensed phase. Additionally, the polymeric glycerol-based flame retardants exhibited good compatibility with UPR matrix. This work explores the high-efficiency flame retardant structures with good compatibility for UPR, promoting the wide application of UPR materials. 

Novel glycerol-based polymerized flame retardants with combined phosphorus structures for preparation of high performance unsaturated polyester resin composites

Polycarbonate (PC) is highly attractive for applications in high-speed railways and airplanes as engineering materials, but suffers from high fire hazards with severe melting dripping during burning. To overcome the challenge, highly effective flame retardants, such as sulfonate derivatives and silicon-based compounds have been developed. Unfortunately, there is still lacking of a systematic method to evaluate the fire risk of these flame-retardant PC composites. Herein, we propose a comprehensive and innovative approach to assess the fire safety of flame-retardant PC composites containing potassium perfluorobutane sulfonate (PPFBS) and a silicon-based flame retardant (PSR) through combining numerous combustion parameters obtained from different measurements. The pyrolysis and combustion characteristics of PC/PPFBS and PC/PSR were studied in detail and revealed that PPFBS and PSR could effectively reduce the activation energy of PC. PSR is effective at reducing the heat and smoke release due to the formation of a Si–C protective layer during combustion. In contrast, PPFBS has no obvious suppression effect on smoke generation, and even shows a combustion-supporting effect under high radiation flux. Based on the analytic hierarchy process (AHP), a comprehensive evaluation model has been established to achieve an objective and comprehensive evaluation of the fire hazards of PC and its composites. This works provides a universal guidance for evaluating fire hazards of flame-retardant polymer composite. 

High-performance flame-retardant polycarbonate composites: Mechanisms investigation and fire-safety evaluation systems establishment

Boron doped C3N5 for photocatalytic nitrogen fixation to ammonia: the key role of boron in nitrogen activation and mechanism

Synthesis and fluorescence properties of rare earth (Eu3+ and Gd3+) complexes with α-naphthylacetic acid and 1,10-phenanthroline

With the advent of the 5G era, preparing conductive polymers to accomplish electromagnetic interference (EMI) shielding, mechanical enhancement, and flame retardancy are of vital importance. Graphite felt (GF) acts as a three-dimensional structure and organophosphorus derivatives containing different valences work as a flame retardant to form a novel EP composite. With GF incorporated into EP, EMI shielding effectiveness (SE) achieves around 60 dB, and absorption is dominated in the X band (8.2–12.4 GHz). Meanwhile, GF could exert a fiber reinforcement effect to enhance the mechanical properties of EP composites, tensile strength and impact strength of EP/GF are increased by 19.1% and 64.2%, respectively. However, owing to the “wick effect” of GF, 20 wt% DOPO-PEPA is added to acquire flame-retardant EP composites. Herein, a potential strategy broadens applications of EP composites in the high-end field and is provided to prepare polymer composites . • A cost-reasonable EP composites composed of 3D GF and two-valence phosphorous derivatives is successfully fabricated. • The EMI SE EP composites achieve around 60 dB in the X band. • The pHRR and THR of EP/GF/20FR are reduced by 53.4% and 35.3%, respectively. • EP composites exhibit potential promise for large-scale production and industrial applications. 

Wei-Min Cai

Papers

Novel glycerol-based polymerized flame retardants with combined phosphorus structures for preparation of high performance unsaturated polyester resin composites

High-performance flame-retardant polycarbonate composites: Mechanisms investigation and fire-safety evaluation systems establishment

Boron doped C3N5 for photocatalytic nitrogen fixation to ammonia: the key role of boron in nitrogen activation and mechanism

Synthesis and fluorescence properties of rare earth (Eu3+ and Gd3+) complexes with α-naphthylacetic acid and 1,10-phenanthroline

Cost-effective graphite felt and phosphorous flame retardant with extremely high electromagnetic shielding