Chain Coordination Research Articles

β‐Myrcene Coordination Polymerization: Experimental and Kinetic Modeling Study

AbstractThe present work presents phenomenological models to describe the coordination polymerization of β‐myrcene using the Ziegler–Natta catalyst system composed by neodymium versatate (NdV3), diisobutylaluminum hydride (DIBAH), and dimethyldichlorosilane. The kinetic parameters required to simulate the reactions are estimated, and the amount of DIBAH used as a chain transfer agent (CTA) is obtained by a data reconciliation strategy since it can participate in side reactions. Several experiments are performed at different conditions to evaluate the impact of key operation variables on the control of monomer conversion and average molar masses. It is shown that the initial NdV3, β‐myrcene, and DIBAH concentrations exert strong influences on the course of the polymerization. The kinetic mechanism of Coordinative Chain Transfer Polymerization (CCTP) fits well with the data of final average molar masses and monomer conversion, while the dynamic trajectories of these variables are fitted better by kinetic mechanisms of more conventional coordination polymerizations, considering site deactivation and termination by chain transfer. In all cases, the proposed models are able to predict the experimental data well after successful parameter estimation and reconciliation of CTA concentrations, indicating that the kinetic mechanism can be characterized by different kinetic regimes.

Front Cover: Non‐π‐Allyl Mechanism for the 1,4‐cis‐Butadiene Polymerization: Theoretical Study of Polymerization via Insertion of Butadiene into Al−C Bond with Cationic Gadolinium Metallocene. (Chem. Asian J. 23/2022)

A novel mechanism for the polymerization of butadiene by cationic gadolinium metallocene in the presence of excess Al(iBu)3 is presented. The absence of an initial Gd-alkyl bond in this reaction system precludes the conventional mechanism by coordinative chain transfer polymerization (CCTP). Density functional theory (DFT) analysis indicates a mechanism in which cationic Gd assists butadiene insertion into one of the Al–C bonds of Al(iBu)3, explaining the 1,4-cis selectivity unique to this catalytic system. More information can be found in the Research Article by Rika Fukushima et al.

Non-π-Allyl Mechanism for the 1,4-cis-Butadiene Polymerization: Theoretical Study of Polymerization via Insertion of Butadiene into Al-C Bond with Cationic Gadolinium Metallocene.

This paper reports a computational study on the specific 1,4-cis polymerization of butadiene catalyzed by the cationic gadolinium metallocene [(C5 Me5 )2 Gd][B(C6 F5 )4 ] combined with excess amount of Al(i Bu)3 . Because this reaction system has no initial Gd-alkyl bond, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by assisting butadiene insertion into one of the Al-C bond of Al(i Bu)3 . The proposed butadiene polymerization mechanism can account for the specific 1,4-cis selectivity of this catalyst system.

Silver alkynyl coordination chains and clusters assembled with sulfonates

The metal cluster can be controlled by adjusting the size of the anionic templates and by using different peripheral organic ligands. In this paper, we employ RCCAg (R = 4-tBu-Ph, Ph, tBu), CF3SO3Ag, NH4X (X = Br, VO3) acting as starting materials to obtain four silver ethynide complexes incorporating the sulfonate ligands, namely, [Ag3(4-tBu-PhCC)2(CF3SO3)]n (1), {[Br@Ag15(PhCC)10(CF3SO3)4][Ag4(PhCC)4][Br@Ag15(PhCC)10(CF3SO3)4]}n (2), [Br@Ag15(tBuCC)10(CF3SO3)4]n (3) and [V2O7@Ag24(tBuCC)14(CF3SO3)6] (4). Single-crystal X-ray analysis revealed that complexes 1–3 display different coordination chain structures, while 4 contain high-nuclearity silver(I) composite clusters enclosing a [V2O7]4− template ion, that are supported by CF3SO3- ligands.

Low-Coordinate Erbium(III) Single-Molecule Magnets with Photochromic Behavior.

The structures and magnetic properties of photoresponsive magnets can be controlled or fine-tuned by visible light irradiation, which makes them appealing as candidates for ternary memory devices: photochromic and photomagnetic at the same time. One of the strategies for photoresponsive magnetic systems is the use of photochromic/photoswitchable molecules coordinated to paramagnetic metal centers to indirectly influence their magnetic properties. Herein, we present two erbium(III)-based coordination systems: a trinuclear molecule {[ErIII(BHT)3]3(dtepy)2}.4C5H12 (1) and a 1D coordination chain {[ErIII(BHT)3(azopy)}n·2C5H12 (2), where the bridging photochromic ligands belong to the class of diarylethenes: 1,2-bis((2-methyl-5-pyridyl)thie-3-yl)perfluorocyclopentene (dtepy) and 4,4′-azopyridine (azopy), respectively (BHT = 2,6-di-tert-butyl-4-methylphenolate). Both compounds show slow dynamics of magnetization, typical for single-molecule magnets (SMMs) as revealed by alternating current (AC) magnetic susceptibility measurements. The trinuclear compound 1 also shows an immediate color change from yellow to dark blue in response to near-UV irradiation. Such behavior is typical for the photoisomerization of the open form of the ligand into its closed form. The color change can be reversed by exposing the closed form to visible light. The chain-like compound 2, on the other hand, does not show significant signs of the expected trans–cis photoisomerization of the azopyridine in response to UV irradiation and does not appear to show photoswitching behavior.

Structures, luminescent properties, and volatile iodine detection of Zn(II) based zigzag coordination chains

Two isostructural luminescent Zn coordination polymers, [Zn(ip)(Cz-Pr-3,6-bpy)2]n·2n(H2O) (1) and [Zn(hip)(Cz-Pr-3,6-bpy)2]n·3n(H2O) (2), where Cz-Pr-3,6-bpy ​= ​3,6-bis(pyridin-4-yl)-9-n-propyl-9H-carbazole, H2ip ​= ​isophthalic acid, and H2hip ​= ​5-hydroxyisophthalic acid, showing good chemical stability have been synthesized under hydro(solvo)thermal conditions. Coordination polymers 1 and 2 both show Zn–dicarboxylate zigzag chains with each Zn(II) center anchoring by two monodentate Cz-Pr-3,6-bpy pendants. Luminescence studies indicate that 1 and 2 emit bright cyan- and blue-light fluorescence, respectively, in solid-state. Of note, 1 and 2 both show detectable fluorescence on–off response with high quenching efficiencies of >97% and visual color change from pale yellow to darker brown upon exposure to iodine vapors. The I2-loaded capacity is gravimetrically determined to be 0.162 ​g ​g−1 for 1 and 0.012 ​g ​g−1 for 2. This makes 1 and 2 to be good dual-responsive optical chemosensors for volatile iodine detection.

The Role of the Bridge in Single-Ion Magnet Behaviour: Reinvestigation of Cobalt(II) Succinate and Fumarate Coordination Polymers with Nicotinamide

Two previously synthesized cobalt(II) coordination polymers; {[Co(μ2-suc)(nia)2(H2O)2]·2H2O}n (suc = succinate(2−), nia = nicotinamide) and [Co(μ2-fum)(nia)2(H2O)2]n (fum = fumarate(2−)) were prepared and thoroughly characterized. Both complexes form 1D coordination chains by bonding of Co(nia)2(H2O)2 units through succinate or fumarate ligands while these chains are further linked through hydrogen bonds to 3D supramolecular networks. The intermolecular interactions of both complexes are quantified using Hirshfeld surface analysis and their infrared spectra, electronic spectra and static magnetic properties are confronted with DFT and state-of-the-art ab-initio calculations. Dynamic magnetic measurements show that both complexes exhibit single-ion magnet behaviour induced by a magnetic field. Since they possess very similar chemical structure, differing only in the rigidity of the bridge between the magnetic centres, this chemical feature is put into context with changes in their magnetic relaxation.

The Design of China's Carbon Audit Framework and The Construction of The Implementation Path under the "Double Carbon" Goal

Under the goal of "double carbon", carbon peaking and carbon neutral work has become the key task specified in the central economic conference. Based on this, this paper analyzes the current situation and obstacles of carbon audit development in China, constructs a carbon audit framework for the current situation and proposes the implementation path of carbon audit: firstly, a three-dimensional evaluation index system is constructed according to the current obstacles of carbon audit, in order to make carbon information flow smoothly, secondly, a coordination chain is constructed consisting of social, governmental and national audit institutions to link up and supervise the carbon emission of enterprises, and finally, the government gradually improves the carbon audit standard according to the problems in practice. Carbon audit standards, new standards can in turn stimulate the generation of new evaluation systems, until the entire carbon audit framework becomes scientifically unified; the implementation path is built around the carbon audit framework, divided into pre-audit stage, implementation stage, assurance stage, and follow-up audit stage.

Supramolecular porous frameworks of two Ni(II) coordination polymers with varying structures, porosities, and magnetic properties

Based on a simple benzimidazole derivative and nickel nitrate, two nickel(II) based supramolecular three-dimensional (3D) porous solids, namely {[Ni(Hbic)2(OH2)2]·H2O}n (1) and {[Ni(Hbic)2(OH2)]·2CH3OH}n (2) (H2bic = 1H-benzimidazole-5-carboxylic acid), were synthesized and characterized. Single crystal X-ray diffraction experiments revealed that compound 1 is a 1D coordination polymer with a linear chain structure while 2 is a 2D metal–organic framework (MOF) with a honeycomb network structure. Interestingly, the coordination chains in 1 and layers in 2 can form stable supramolecular 3D porous frameworks sustained by hydrogen bonding interactions and intermolecular π–π interactions. The distinct permanent porosity of the frameworks was established by N2 adsorption experiments. The Ni2+ centers in the two frameworks locate in two different distorted octahedral coordination environments, which lead to the varying crystal color with the effect of diverse supramolecular packing of the crystal structures. Magnetic investigation revealed that the frameworks exhibit significant easy-axis magnetic anisotropy with the zero-field splitting parameter D = -27.8 and −16.5 cm−1 for 1 and 2, respectively. However, no field-induced slow magnetic relaxation behaviors can be detected for 1 and 2. The foregoing results highlight that simple organic molecule can be used for the preparation of supramolecular magnetic frameworks with permanent porosity and coordination polymers-based supramolecular porous frameworks can act as a platform for tunable porosity and magnetic properties.

IPP/PE Multiblock Copolymers for Plastic Blend Recycling Synthesized by Coordinative Chain Transfer Polymerization

Recycling of blends of widely used plastics is a key challenge of the envisioned circular economy, and thus, protocols permitting the efficient synthesis of effective compatibilizers are highly desirable. We report herein that coordinative chain transfer polymerization permits the efficient one-pot synthesis of multiblock architectures of strictly linear polyethylene or high-density polyethylene (HDPE) and isotactic polypropylene (iPP). Various block copolymers having an iPP backbone and HDPE side chains were synthesized and used to compatibilize HDPE/iPP plastic blends. The synthesized block copolymers differ in their overall molecular weights and have different HDPE side chain lengths and numbers. A block copolymer with a molecular weight of Mp = 33,700 g × mol–1 including 4.5 HDPE side chains with a molecular weight of Mn = 600 g × mol–1 showed the highest efficiency for compatibilizing 30/70 wt % blends of HDPE/iPP with a 5 wt % compatibilizer addition. This block copolymer is also superior to commercially available compatibilizers.

Novel CuI coordination polymer self-assembled from 2,5-bis(pyridin-4-yl)-1,3,4-oxadiazole and thiocyanate ions: Synthesis, structural characterization, Hirshfeld surface analysis, thermal and magnetic studies

The synthesis and crystal structure of one-dimensional (1-D) coordination polymer from an angular dipyridyl ligand 2,5-bis(pyridine-4-yl)-1,3,4-oxadiazole (4-pox) and CuCl2⋅2H2O, [CuI(4-poxH)(SCN)(μ1,3-SCN)]n (named complex 1), are reported. The investigated copper(I) complex crystallizes in the monoclinic crystal system with space group P21/n. UV–vis and FTIR suggest the co-presence of the 4-pox ligand and the pseudohalide, in the isolated complex. This was confirmed by a crystallographic study which shows that the copper is in a tetrahedral environment, linked to two thiocyanate groups and to two nitrogen atoms, one belonging to the pyridine ring and the others to thiocyanate group. The crystallographic study also reveals the protonation of the unbound organic ligand pyridine. The crystal cohesion is assured by different intermolecular hydrogen bonds, π–π stacking, and coordination bonds (N–Cu and S–Cu). Therefore, the one-dimensional coordination chains are further interconnected by hydrogen bonds and π–π stacking to from a three-dimensional supramolecular framework. This behaviour was confirmed by Hirshfeld surface analysis. The thermal analysis reveals that complex 1 is thermally stable up to 160 °C. The magnetic measurements indicated the diamagnetic nature of this CuI coordination polymer.

Influence of external N‐containing donors on the neodymium‐based catalytic system for 1,3‐butadiene polymerization

AbstractEvaluation of the heteroatom tolerance capability of neodymium‐based precatalysts and its accompanied catalytic influences is of great significance for industrial production of polybutadienes because the corresponding active species is highly sensitive to heteroatom‐based impurities that are usually inevitable in the polymerization system. Based this consideration, the present research disclosed a systematical study of the influence of N‐containing donors on a ternary Nd‐based system of Nd(vers)3/DIBAH/TEA/EASC. It was found that the presence of 1% of such donors, regardless of their types that bears different electronic/steric properties, brought little influence on the catalytic activities as well as the cis‐1,4‐stereoselectivities of the catalytic system, giving cis‐1,4‐enriched polybutadienes with comparable yields. Furthermore, the presence of such a concentration of N‐donor also brought little influence on the coordinative chain transfer polymerization behaviors of the system, giving narrowly distributed polybutadiene products in a well‐controlled manner. Nevertheless, further increasing the concentration of N‐donors to >1% eventually led to a gradually decreased polymer yields due to the poison of the corresponding active species, and the obtained catalytic efficiencies were highly dependent on the types of N‐donors. The influence of the N‐donor on other parameters of the products, that is, molecular weights, polydispersities, and so forth, were also investigated, and the specific reasons were proposed.

Coordinative Chain Transfer Polymerization of Sustainable Terpene Monomers Using a Neodymium-Based Catalyst System.

The present investigation involves the coordinative chain transfer polymerization (CCTP) of biobased terpenes in order to obtain sustainable polymers from myrcene (My) and farnesene (Fa), using the ternary Ziegler–Natta catalyst system comprising [NdV3]/[Al(i-Bu)2H]/[Me2SiCl2] and Al(i-Bu)2H, which acts as cocatalyst and chain transfer agent (CTA). The polymers were produced with a yield above 85% according to the monomeric consumption at the end of the reaction, and the kinetic examination revealed that the catalyst system proceeded with a reversible chain transfer mechanism in the presence of 15–30 equiv. of CTA. The resulting polyterpenes showed narrow molecular weight distributions (Mw/Mn = 1.4–2.5) and a high percent of 1,4-cis microstructure in the presence of 1 equiv. of Me2SiCl2, having control of the molecular weight distribution in Ziegler–Natta catalytic systems that maintain a high generation of 1,4-cis microstructure.

Preparation of Well-Controlled Isotactic Polypropylene-Based Block Copolymers with Superior Physical Performance via Efficient Coordinative Chain Transfer Polymerization

Preparation of Well-Controlled Isotactic Polypropylene-Based Block Copolymers with Superior Physical Performance via Efficient Coordinative Chain Transfer Polymerization

Gap switching in metal-organic coordination chains

We predict two switchable one-dimensional (1D) spin-polarized semiconductors based on metal-organic coordination chains constructed out of Fe, V, and zwitterionic quinone (ZQ) molecules using first-principle density functional theoretical analysis. The Fe-ZQ coordination chain can be converted from a semiconductor to a half-metal when oxidized by chlorine (Cl). Upon chlorination, the magnetic moment of the Fe-ZQ is increased from 4 μB to 5 μB, per iron atom. In addition, the bimetallic (Fe-ZQ-V-ZQ) ferromagnetic semiconducting coordination chain with a very small energy gap of only 90 meV can be converted to an antiferromagnetic semiconductor with a large gap of more than 1 eV when oxidized by chlorine. Its magnetic moment is found to be 8 μB per heterobimetallic unit (Fe and V) after chlorination, and 7 μB without chlorine. These unique properties, namely a switchable or reversible electronic and magnetic characteristics with a transition between different semiconducting states, make these coordination chains to be highly promising candidates for specific applications as multi-functional switch in nanoelectronics and spintronics.

Terpene Coordinative Chain Transfer Polymerization: Understanding the Process through Kinetic Modeling.

The interest in the Coordinative Chain Transfer Polymerization (CCTP) of a family of naturally occurring hydrocarbon monomers, namely terpenes, for the production of high-performance rubbers is increasing year by year. In this work, the synthesis of poly(β-myrcene) via CCTP is introduced, using neodymium versatate (NdV3), diisobutylaluminum hydrade (DIBAH) as the catalytic system and dimethyldichlorosilane (Me2SiCl2) as the activator. A bimodal distribution in the GPC signal reveals the presence of two populations at low conversions, attributable to dormants (arising from reversible chain transfer reactions) and dead chains (arising from termination and irreversible chain transfer reactions); a unimodal distribution is generated at medium and high conversions, corresponding to the dominant species, the dormant chains. Additionally, a mathematical kinetic model was developed based on the Method of Moments to study a set of selected experiments: ([β-myrcene]0:[NdV3]0:[DIBAH]0:[Me2SiCl2]0 = 660:1:2:1, 885:1:2:1, and 533:1:2:1). In order to estimate the kinetic rate constant of the systems, a minimization of the sum of squared errors (SSE) between the model predicted values and the experimental measurements was carried out, resulting in an excellent fit. A set of the Arrhenius parameters were estimated for the ratio [β-myrcene]0:[NdV3]0:[DIBAH]0:[Me2SiCl2]0 = 660:1:2:1 in a temperature range between 50 to 70 °C. While the end-group functionality (EGF) was predominantly preserved as the ratio [β-myrcene]0:[NdV3]0 was decreased, higher catalytic activity was obtained with a high ratio.

Ortho-substituent effect on metal coordination geometry, chain microstructure and polymer properties in α-diimine nickel-catalyzed long chain α-Olefin polymerization

The tuning of polyolefin microstructure, including the branching density and branching distribution, through the ligand modification in transition metal-based catalysts has received considerable interest. In this work, we present the synthesis and characterization of a series of α-diimine Ni(II) catalysts containing bulky diarylmethyl moiety and varied steric substituents, and a systematic investigation on the catalytic behavior of these catalyst for 1-octene and 1-decene polymerization. Ni3 with ortho-diisopropyl substituents adopts a common distorted tetrahedral geometry, while a rare square planar geometry is observed for Ni4 with ortho-phenyl substituents. The ortho-substituent effect on the preference of insertion fashion (1,2 or 2,1-insertion) and chain-walking in long chain α-olefin polymerization is also established. Highly branched amorphous polyolefin can be obtained by the unsymmetrical catalyst with ortho-alkyl substituents (H, Me, iPr) in which the major 1,2-insetion pathway was observed, whereas moderate branched semicrystalline polyolefin can be produced by the unsymmetrical catalyst with ortho-phenyl substituents, which showed a significant increase in 2,1-insertion. Most interestingly, the branching distribution analysis through 13C NMR indicated that the polymer obtained by Ni3 gave the higher percentage of long-chain branches relative to methyl branches, while Ni4 afforded the polymer with methyl branches being predominant. These significant differences in coordination geometry and catalytic behavior between Ni3 and Ni4 may be associated with the unique steric congestion of the ortho-phenyl substituents. In particular, the comparative investigation of the mechanical properties of the polymers obtained by Ni3 and Ni4 was also performed.

Role of big data analytics capabilities to improve sustainable competitive advantage of MSME service firms during COVID-19 – A multi-theoretical approach

The extant literature suggests that digital technologies (big data analytics, artificial intelligence, blockchain) help firms gain a competitive advantage. However, the studies do not focus on the micro, small and medium enterprises (MSME) sector. Moreover, MSMEs face various challenges, including significant supply chain disruption due to the COVID-19 pandemic. Hence, there was an urgent requirement to shift to digital technologies to survive during this difficult time. In the context of MSME, various positive changes are discussed in the recent literature. However, a dearth of studies discusses the role of big data analytics capabilities (BDAC) to gain sustainable competitive advantage (SCA). Our study aims to fill this gap and answer this question – How do BDAC help MSMEs gain SCA? To understand the phenomenon, we receive theoretical support from organizational information processing theory (OIPT) and institutional theory (IT). We develop a conceptual framework that links BDAC and SCA through supply chain coordination, swift trust, and supply chain risk. Additionally, the age and size of the firm are used as control variables. The data is collected from Indian service sector employees of MSMEs, resulting in 497 usable responses. We use PLS-SEM using Warp PLS 7.0 to test the hypotheses. A critical finding is that the BDAC indirectly impacts the SCA. Finally, the other findings, limitations, and scope for future research are discussed.

Preparation of star-shaped polybutadiene via coordinative chain transfer polymerization

Preparation of star-shaped polybutadiene via coordinative chain transfer polymerization

Effect of different chain transfer agents in the coordinative chain transfer oligomerization of dec-1-ene

Our recently developed new procedure was recalled to synthesize saturated polyalphaolefin (PAO)-based lubricants, in situ in a single step manner, using different chain transfer agents (CTA)s. To this aim, coordinative chain transfer oligomerization (CCTO) of dec-1-ene monomer was conducted to achieve saturated PAOs employing [Ti{2,2ʹ-(OC6H2-4,6-tBu2)2NHMePhMeNH}Cl2] complex and MAO as pre-catalyst and cocatalyst, respectively. Along with catalyst, various mole fractions of diethylzinc (ZnEt2), triethylaluminium (TEAL), and n-butylethylmagnesium (nBuEtMg) were utilized as CTAs during oligomerization procedure. Results disclosed that ZnEt2 lead to a reversible chain transfer reaction but TEAL, and nBuEtMg caused an irreversible chain transfer manner. Molecular weight of the synthesized PAO samples decreased by utilizing CTAs. Kinetic and 13C-NMR results exhibited that the catalyst consumption diminished and PAO tacticity degraded in CCTO procedure in comparison to the traditional oligomerization process. Furthermore, 1HNMR results confirmed the preparation of fully saturated PAO chains in the presence of proper amounts of ZnEt2 and nBuEtMg, which reveals their high efficiency in performing the CCTO mechanism. Kinematic viscosity (KV) and viscosity index (VI) values of the fabricated samples were comparable with commercial PAOs which are traditionally produced by the dangerous BF3 catalyst in industry.