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Li 2 O-Al 2 O 3 -SiO 2 (LAS) glass ceramics have a low coefficient of thermal expansion, high mechanical strength, and excellent chemical stability. With advancements in glass ceramics, researchers have explored using LAS glass ceramics with transition metal doping and rare earth doping. Most previous studies have studied the impact of rare earth element doping on crystallization primarily in the context of conventional nucleating agents present in glass. In this study, we aimed to investigate the impact of Y 2 O 3 and La 2 O 3 on LAS glasses in the presence of undoped nucleating agents. The crystallization mechanism of La 2 O 3 and Y 2 O 3 doped LAS glass ceramics was studied using differential scanning calorimetry. The crystallization kinetics of the glasses were analyzed using model-free and modeling methods. Moreover, the activation energy of crystallization and the indices of crystallization and growth of glass ceramics were calculated, and the crystalline phase and microstructure of the samples were characterized. All three fractions of the LAS glass showed consistent crystallization under different calculation methods. The glass doped with La 2 O 3 and Y 2 O 3 exhibited two- or three-dimensional growth during crystallization, promoting crystallization in the LAS glass. The Y 3 La 0 sample demonstrated the most favorable crystallization effect. In the presence of an undoped nucleating agent, rare earth elements can enhance glass crystallization; this new idea can be utilized for the development of new materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The fluoro-substituted 2,6-bis(arylimino)pyridine dichlorocobalt complexes, [2-{CMeN(2,6-(Ph 2 CH) 2 -3,4-F 2 C 6 H)}-6-(CMeNAr)C 5 H 3 N]CoCl 2 (Ar = 2,6-Me 2 C 6 H 3 Co1, 2,6-Et 2 C 6 H 3 Co2, 2,6-iPr 2 C 6 H 3 Co3, 2,4,6-Me 3 C 6 H 2 Co4, 2,6-Et-4-MeC 6 H 2 Co5), were synthesized in good yield from the corresponding unsymmetrical N , N , N '-ligands, L1-L5. Besides characterization of Co1-Co5 by FT-IR spectroscopy, 19 F NMR spectroscopy and elemental analysis, the molecular structures of Co2 and Co5 were also determined highlighting the unsymmetrical nature of the terdentate ligand and the pseudo -square pyramidal geometry about the metal center. When either MAO or MMAO were employed as activators, Co1-Co5 were able to achieve a wide range of catalytic activities for ethylene polymerisation. Co5/MAO exhibited the highest activity of the study at 60 °C (7.6 × 10 6 g PE mol -1 (Co) h -1 ) which decreased to 3.3 × 10 6 g PE mol -1 (Co) h -1 at 80 °C. In addition, it was found that the polymerisation activity increased as the steric hindrance imparted by the ortho groups was enhanced (for MMAO: Co3 > Co5 > Co2 > Co1 > Co4), a finding that was supported by DFT calculations. Furthermore, it was shown that particularly high molecular weight polyethylene could be generated (up to 483.8 kg mol -1 ) when using Co5/MMAO at 30 °C, while narrow dispersities ( M w / M n range: 1.8-4.7) and high linearity ( T m > 131.4 °C) were a feature of all polymers produced. By comparison of Co3 with its non-fluorinated analogue using experimental data and DFT calculations, the substitution of fluorides at the meta - and para -positions was demonstrated to boost catalytic activity and improve thermal stability., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A set of five related bis(imino)-6,7-dihydro-5 H -quinoline-cobalt(ii) complexes, [2-(ArN = CPh)-8-(NAr)-C 9 H 8 N]CoCl 2 (Ar = 2,6-Me 2 C 6 H 3 Co1, 2,6-Et 2 C 6 H 3 Co2, 2,6-i-Pr 2 C 6 H 3 Co3, 2,4,6-Me 3 C 6 H 2 Co4, 2,6-Et 2 -4-MeC 6 H 2 Co5), have been synthesized in reasonable yield by the template reaction of cobalt(ii) chloride hexahydrate, 2-benzoyl-6,7-dihydro-5 H -quinolin-8-one and the corresponding aniline. The molecular structures of Co1 and Co4 highlight both the differences in the two imino-carbon environments (phenyl-capped chain vs. cyclic) and also the steric properties exerted by the bulky N imine -aryl groups. On pre-treatment with either modified methylaluminoxane (MMAO) or methylaluminoxane (MAO), all complexes proved productive catalysts for the polymerization of ethylene. In particular, Co1/MAO was the most active reaching a very high level of 1.62 × 10 7 g PE per mol (Co) per h over a 30 minute run time. Owing to the presence of the imino-phenyl substituent, Co1-Co5 were able to exhibit good thermal stability by displaying appreciable catalytic activity at temperatures between 50 and 80 °C, generating polyethylenes with narrow dispersities ( M w / M n range: 1.66-3.28). In particular, the least sterically bulky precatalysts, Co1 and Co4 formed polyethylene waxes ( M w range: 1.94-5.69 kg per mol) with high levels of vinyl unsaturation as confirmed by high temperature 1 H/ 13 C NMR spectroscopy and by IR spectroscopy., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A family of unsymmetrical 2-(2,4-bis(di(4-methoxyphenyl)methyl)-6-MeC 6 H 2 N)-6-(1-(arylimino)ethyl)pyridine-cobalt dichloride complexes has been synthesized and characterized by NMR spectroscopy, FT-IR spectroscopy and elemental analysis as well as single crystal X-ray diffraction for Co2 and Co4. Activated with either MAO or MMAO, all the cobalt precatalysts displayed high activities toward ethylene polymerization and produced highly linear polyethylenes with high molecular weights as well as wide polydispersities; for example, the performance using Co1/MAO at 50 °C reached 9.17 × 10 6 g PE (mol of Co) -1 h -1 with the production polyethylene of molecular weight as high as M w = 3.14 × 10 5 g mol -1 , T m = 134.3 °C besides its wide polydispersity of M w / M n of 54.6. Besides the terminal vinyl group of the resultant polyethylenes, it is rare for a late-transition metal catalyst to achieve highly linear polyethylenes with not only wide polydispersity but also high molecular weights, being similar to high-density polyethylenes produced using Phillips catalyst., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)