Vinyl-type polymerization of norbornene as well as random copolymerization of norbornene with styrene was studied using a series of copper complexes-MAO. The precatalysts used here are copper complexes with β-ketoamine ligands based on pyrazolone derivatives and the molecular structure of complex 4 was determined using X-ray analysis. All of these catalyst systems are moderately active for the vinyl-type polymerization of norbornene and random copolymerization of norbornene with styrene. The random copolymers obtained suggest that only one type of active species is present. Gel permeation chromatography (GPC) and NMR indicate that the copolymers are 'true' copolymers. The copolymerization reactivity ratios (r NBE = 20.11 and r Sty = 0.035) indicate a much higher reactivity of norbornene, which suggests a coordination polymerization mechanism. The solubility and processability of the copolymers are improved relative to polynorbornene and the thermostability of the copolymers is improved relative to polystyrene.

C 4 H 4 O 4 Pb, monoclinic, P12 1 /c1(no. 14), a =9.715(2) Å, b =6.753(2) Å, c =9.044(2) Å, b =106.931(2)°, V =567.6 Å 3 , Z =4,R gt (F) =0.028, wR ref (F 2 ) =0.075, T =291 K. Source of materialLead nitrate (0.0828 g, 0. 25 mmol), succinate (0.0148 g, 0.125 mmol), ethanol (2 ml) and water (15 ml) were placed in a23ml, Teflon-lined, stainless-steel Parr bomb. The bomb was heated at 433 Kf or 5d ays and cooled to room temperature at 5Kh − 1 . Brown block crystals were obtained in 10 %yield. Experimental detailsHatoms bonded to Catoms were placed in calculated positions with d(C-H) =0.93 -0.97 Å and included in the riding model approximation. The positional parameters of Hatoms bonded to N atoms were refined independently. For all Hatoms the fixed values U iso (H) =1.2 U iso (C,N) were applied. DiscussionPb(II) cations form ag roup of coordination polymers and polynuclear complexes which display interesting structural features as aconsequence of the large radius, adoption of different coordination numbers and the possible occurrence of as tereochemically active lone pair [1]. The design of crystal structures and control of molecular arrangements of coordination polymers have attracted much attention in recent years [2]. Simple monocarboxylates and dicarboxylates that give crystalline polymers have been reported [1]. Lead succinate, which prepared by the reactions of the corresponding metal carbonates with a succinic acid, has acubic coordination of lead [3] and exhibits a phase transition from tetragonal to acubic at 433 K[4]. Here we synthesized the polymorph of PbC 4H4O4 under lead(II) nitrate and succinic acid conditions, which has lead in a y-bicapped square antiprismatic geometry. In the asymmetric unit of the title compound, the Pb(II) atom is coordinated by six Oatoms from 4succinate ligands, there is a gap on one side, suggesting astereochemically active lone pair on the lead.The leads linked through the organic backbone of the succinates and the Pb 2 O 2 rings to form athree dimensional structure.

The major challenges of photothermal therapy (PTT) toward clinical application are the severe skin injury and inflammation response associated with high power laser irradiation. Herein, polydopamine nanoparticles (PDA-EST and PDA-RAL) targeted to estrogen receptor 𝜶 (ER𝜶) for efficient ablation of breast tumor under a low irradiation density of 0.1 W cm -2 are reported. These nanoparticles are capable of recruiting ER𝜶 on their surface and induce a complete ER𝜶 degradation via localized heat. Owing to the ER𝜶 targetability, PDA-EST and PDA-RAL strongly suppress the proliferation of breast cancer cells without causing significant inflammation. This work provides a generalized method for enhancing PTT efficacy under low irradiation density.

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Key indicatorsSingle-crystal X-ray study T = 292 K Mean (C-C) = 0.004 Å R factor = 0.038 wR factor = 0.110 Data-to-parameter ratio = 17.5For details of how these key indicators were automatically derived from the article, see