Organometallic Polymers Research Articles

Ruthenium(II) N-heterocyclic carbene polymer based sensors for detection of predatory drugs like ketamine and scopolamine.

The current demand in the field of abusive drug research is to have a highly sensitive and rapid method for detecting ketamine and scopolamine, which are frequently used in drug-facilitated sexual assaults administered via beverages and food. We report here the first electrochemical sensors of N-heterocyclic carbene (NHC) coordinated ruthenium organometallic 1-dimensional polymers and their multi-walled carbon nano tube (MWCNT)-based composite for detecting ketamine and scopolamine. The preparation of ruthenium NHC organometallics and the MWCNT composite as sensors offers significant advantages for electrochemical applications, with enhanced sensitivities of 121.979 and 3.273 μA μM-1 cm-2 for ketamine and scopolamine, respectively, and selectivity in sensing applications. The complex-carbon composite sensor has a low limit of detection i.e., 0.194 and 3.18 nM for ketamine and scopolamine identification, respectively. Alongside, the selectivity of the composite sensor was evaluated in the presence of other blood constituents, and the study evidenced remarkable discernment towards the title drugs. Furthermore, real-time analyses using the composite sensor demonstrated quantitative identification of ketamine and scopolamine. Therefore, this innovation has the potential to provide valuable tools for forensic investigations and address the urgent need for real-time detection of date rape drugs. This contribution demonstrates a robust proof-of-concept that emphasizes the importance of creating non-enzymatic, environmentally friendly, and cost-effective sensors for on-site sensing applications as point-of-care devices.

Organometallic Polymer Constructed by Active Fe-C12N8 Centers for Boosting Sodium-Ion Storage.

Organic-metal coordination materials with rich structural diversity are considered as promising electrode materials for rechargeable sodium-ion batteries. However, the electrochemical performance can be constrained by the limited number of active sites and structural instability under the discharge/charge process. Herein, organometallic polymer microspheres (Fe-PDA-220) with a unique d-π conjugated structure was designed and successfully constructed through a simple synchronous polymerization and coordination reactions. Polymerization of phenylenediamine was initiated by Fe3+ and Fe2+ ions generated synchronously during the polymerization integrated with poly-aminoquinone chains to form Fe-C12N8 active centers. Used as electrode materials for sodium-ion batteries, the distinctive Fe-C bond significantly boosts the structural stability, and the π-d conjugation system could facilitate electron transfer. A high reversible capacity of 345 mAh g-1 was delivered at 0.1 A g-1 and a capacity of 106 mAh g-1 was maintained even after discharged/charged at 1.0 A g-1 for 5000 cycles, outperforming most reported coordination materials. Spectroscopic and electronic analyses revealed that a two-electron reaction occurred per active unit, accompanied by the reversible redox evolution of the C=N groups and Fe ions during the sodiation/desodiation. This work provides a promising and efficient strategy for boosting the electrochemical performance of organic electrode materials by the design of organometallic polymers.

Organometallic Polymer Constructed by Active Fe−C12N8 Centers for Boosting Sodium‐Ion Storage

AbstractOrganic‐metal coordination materials with rich structural diversity are considered as promising electrode materials for rechargeable sodium‐ion batteries. However, the electrochemical performance can be constrained by the limited number of active sites and structural instability under the discharge/charge process. Herein, organometallic polymer microspheres (Fe‐PDA‐220) with a unique d‐π conjugated structure was designed and successfully constructed through a simple synchronous polymerization and coordination reactions. Polymerization of phenylenediamine was initiated by Fe3+ and Fe2+ ions generated synchronously during the polymerization integrated with poly‐aminoquinone chains to form Fe−C12N8 active centers. Used as electrode materials for sodium‐ion batteries, the distinctive Fe−C bond significantly boosts the structural stability, and the π‐d conjugation system could facilitate electron transfer. A high reversible capacity of 345 mAh g−1 was delivered at 0.1 A g−1 and a capacity of 106 mAh g−1 was maintained even after discharged/charged at 1.0 A g−1 for 5000 cycles, outperforming most reported coordination materials. Spectroscopic and electronic analyses revealed that a two‐electron reaction occurred per active unit, accompanied by the reversible redox evolution of the C=N groups and Fe ions during the sodiation/desodiation. This work provides a promising and efficient strategy for boosting the electrochemical performance of organic electrode materials by the design of organometallic polymers.

Sustainable Formate Production via Highly Active CO2 Hydrogenation Using Porous Organometallic Polymer with Ru-PNP Active Sites.

Efforts to combine the advantages of homogeneous catalysts in terms of activity with the ease of separation process offered by heterogeneous catalysts continue to be actively pursued in the field of catalyst development. Heterogeneous catalysts were synthesized from Ru-MACHO organometallic compounds, recognized for their high hydrogenation catalytic activity linked to the active site of the Ru-PNP motif, through direct polymerization utilizing the Friedel-Crafts reaction. These catalysts were then applied for the conversion of greenhouse gas carbon dioxide (CO2) into formate via hydrogenation, exhibited with a record-high turnover frequency of 31,700 and a productivity of 36,100 kgformate/(kgcatalyst·d). Furthermore, the facile separation characteristics and recyclability of the heterogeneous catalysts were confirmed.

The Development and Atomic Structure of Zinc Oxide Crystals Grown within Polymers from Vapor Phase Precursors.

Sequential infiltration synthesis (SIS), also known as vapor phase infiltration (VPI), is a quickly expanding technique that allows growth of inorganic materials within polymers from vapor phase precursors. With an increasing materials library, which encompasses numerous organometallic precursors and polymer chemistries, and an expanding application space, the importance of understanding the mechanisms that govern SIS growth is ever increasing. In this work, we studied the growth of polycrystalline ZnO clusters and particles in three representative polymers: poly(methyl methacrylate), SU-8, and polymethacrolein using vapor phase diethyl zinc and water. Utilizing two atomic resolution methods, high-resolution scanning transmission electron microscopy and synchrotron X-ray absorption spectroscopy, we probed the evolution of ZnO nanocrystals size and crystallinity level inside the polymers with advancing cycles─from early nucleation and growth after a single cycle, through the formation of nanometric particles within the films, and to the coalescence of the particles upon polymer removal and thermal treatment. Through in situ Fourier transform infrared spectroscopy and microgravimetry, we highlight the important role of water molecules throughout the process and the polymers' hygroscopic level that leads to the observed differences in growth patterns between the polymers, in terms of particle size, dispersity, and the evolution of crystalline order. These insights expand our understanding of crystalline materials growth within polymers and enable rational design of hybrid materials and polymer-templated inorganic nanostructures.

Kinetic control over the chiral-selectivity in the formation of organometallic polymers on a Ag(110) surface

Methods to control chiral-selectivity in molecular reactions through external inputs are of importance, both from a fundamental and technological point of view. Here, the self-assembly of prochiral 6,12-dibromochrysene monomers on Ag(110) is studied using scanning tunneling microscopy. Deposition of the monomers on a substrate held at room temperature leads to the formation of 1D achiral organometallic polymers. When the monomers are instead deposited on a substrate held at 373 K, homochiral organometallic polymers consisting of either the left- or right-handed enantiomer are formed. Post-deposition annealing of room temperature deposited samples at >373 K does not transform the achiral 1D organometallic polymers into homochiral ones and thus, does not yield the same final structure as if depositing onto a substrate held at the same elevated temperature. Furthermore, annealing promotes neither the formation of 1D covalently-coupled polymers nor the formation of graphene nanoribbons. Our results identify substrate temperature as an important factor in on-surface chiral synthesis, thereby demonstrating the importance of considering kinetic effects and the decisive role they can play in structure formation.

A neutral pH all-polymer redox flow battery employing organic and organometallic redox active polymers

Aqueous all-polymer redox flow batteries (APRFBs) working with size exclusion membranes are safe, low-cost, scalable solutions for energy storage applications. However, their development is still limited owing to challenges in optimizing the redox potential and solution viscosity of the polymers to deliver optimal energy density. Herein, we demonstrate an APRFB composed of ferrocene and viologen-based polymers with tunable redox potential. The theoretical calculations and electrochemical measurements reveal the contribution of HOMO energy change and polyelectrolyte dynamics in the charge transfer process with an increase in the molecular weight of the Catholyte-P. The electrochemical experiments yielded reasonable activity of the Catholyte-P24 and Anolyte-P12 with an oxidation rate constant of 1.26 × 10−4 cm s−1 and a reduction rate constant of 5.38 × 10−3 cm s−1, respectively. The application of synthesized polymers with size exclusion membrane yielded a 0.85 V APRFB with energy efficiency up to 72%, capacity retention of 99.93% per cycle at 10 mA cm−2, demonstrated energy density of 2.6 W h L−1, and capacity retention of >82% over continuous 250 cycles.

Complex isomerism influencing the textural properties of organometallic [Cu(salen)] porous polymers: paramagnetic solid-state NMR characterization and heterogeneous catalysis.

Although organometallic porous polymer networks are recognized as promising heterogeneous catalysts, the relationship between ligand/monomer geometry and network parameters is usually not well understood due to the lack of atom-resolved characterization methods for the amorphous network matrix. In this work, a series of copper(II) salen-type metal complexes was synthesized, using trans- and cis-1,2-diaminocyclohexane segments, and thoroughly characterized by single-crystal X-ray diffraction and solution- and solid-state NMR spectroscopy. Terminal ethynyl groups of the complexes were then transformed into polyacetylene chains by coordination chain-growth homopolymerization, resulting in highly porous (458-655 m2 g-1) organometallic polymer networks with a copper(II) ion content of about 12 wt%. The presence of paramagnetic copper(II) moieties in these complexes and respective polymer networks required the application of tailored NMR techniques, which together with X-ray crystallography and DFT calculations of the paramagnetic NMR shifts made it possible to investigate the differences in the complex geometry in liquid, powder and crystalline form and compare it with the complex geometry in polymer networks. All prepared organometallic polymer networks were also tested as heterogeneous catalysts for styrene oxidation with uncommonly high substrate conversions and compared with their low-molecular-weight analogues. The high reusability of such heterogeneous polymer-based catalysts was also proven.

Controlling the thermoelectric properties of organo-metallic coordination polymers through backbone geometry.

Poly(nickel-benzene-1,2,4,5-tetrakis(thiolate)) (Ni-btt), an organometallic coordination polymer (OMCP) characterized by the coordination between benzene-1,2,4,5-tetrakis(thiolate) (btt) and Ni2+ ions, has been recognized as a promising p-type thermoelectric material. In this study, we employed a constitutional isomer based on benzene-1,2,3,4-tetrakis(thiolate) (ibtt) to generate the corresponding isomeric polymer, poly(nickel-benzene-1,2,3,4-tetrakis(thiolate)) (Ni-ibtt). Comparative analysis of Ni-ibtt and Ni-btt reveals several common infrared (IR) and Raman features attributed to their similar square-planar nickel-sulfur (Ni-S) coordination. Nevertheless, these two polymer isomers exhibit substantially different backbone geometries. Ni-btt possesses a linear backbone, whereas Ni-ibtt exhibits a more undulating, zig-zag-like structure. Consequently, Ni-ibtt demonstrates slightly higher solubility and an increased bandgap in comparison to Ni-btt. The most noteworthy dissimilarity, however, manifests in their thermoelectric properties. While Ni-btt exhibits p-type behavior, Ni-ibtt demonstrates n-type carrier characteristics. This intriguing divergence prompted further investigation into the influence of OMCP backbone geometry on the electronic structure and, particularly, the thermoelectric properties of these materials.

A platinum-based photothermal polymer with intermolecular/ligand-to-ligand charge transfer for efficient and sustainable solar-powered desalination

A platinum-based organometallic polymer is developed with a broad absorption spectrum and high photo-to-thermal conversion capability, which can be used to fabricate a solar evaporator for seawater desalination with high operational stability.

On‐Surface Ullmann‐Type Coupling: Reaction Intermediates and Organometallic Polymer Growth

AbstractUllmann‐type coupling is the most widely used on‐surface reaction to form rationally designed bottom‐up molecular nanoarchitectures. A commonly observed reaction product in this reaction is an organometallic phase, however little is known about the formation of this phase. The on‐surface polymerization of the prochiral precursor 6,12‐dibromochrysene (DBCh) on Ag(111) is studied. Upon annealing of DBCh on Ag(111), a linear organometallic polymer forms. However, the delicate energy balance involved in the polymerization of DBCh is such that, at room temperature, several reaction intermediates, which eventually lead to the formation of the organometallic polymer, can be observed experimentally. Organometallic monomers, dimers, and trimers are finds, that self‐assemble into distinct networks. The experimental availability of these reaction intermediates provides key insights into the formation of the organometallic polymer. Comparing the chirality of the intermediates and the polymer sheds additional light on the reaction mechanism leading to the formation of the polymer. The main finding is that the organometallic polymer is not formed by a simple coupling of the reaction intermediates, but rather requires the breaking and re‐establishing of the C─Ag bonds. Additionally, a Br‐enhanced growth mode is observed, where the split‐off halogens align the polymers, which results in an increased polymer length.

Transition Metal Triple-decker Sandwich Complexes Containing Group 13 Elements.

Transition metal triple-decker complexes are an interesting class of sandwich complexes that engrossed great attention due to their structures and properties. Over the decades, synthesis of triple-decker complexes featuring homocyclic, heterocyclic or π-conjugated rings as middle decks have been abundantly reported. In this regard, the chemistry of such complexes bearing boron in the middle deck are well explored due to the ability of boron-containing cycles to readily coordinate bifacially with metal atoms thereby forming triple-decker complexes. On the other hand, electron counting rules and theoretical calculations have strengthened our knowledge of the structure and bonding in these complexes. Further, these complexes can be used as synthons to generate organometallic polymers having interesting electronic, optical and magnetic properties that can be appropriately tuned to cater to a wide range of applications. In our quest for novel metallaboranes and metallaheteroboranes, we have been successful in isolating various triple-decker complexes that feature boron in the middle deck. This review explained elaborately the synthesis, structures, and bonding in such complexes reported by us and others.

A Conjugated Polymer Bearing Perylenediimide (PDI) and Ferrocene (Fc) Exhibiting Stable Data‐Storage Performance

AbstractPolymeric materials have been widely researched and used as active‐layers to fabricate data‐storage resistance random‐access memory (ReRAM) devices. Nevertheless, the problems as drift voltage, weak stability, and low reproducibility largely restrict their practical application in next‐generation memory systems, mainly induced by the molecular stacking defects that limited the efficient charge‐carrier migration throughout the active‐layers. Thus, how to weaken the molecular stacking defects and thus improve the overall ReRAM performance is a scientific issue that needs to be solved urgently. In this work, an organometallic polymer 5,12‐di(thiophen‐2‐l)‐2,9‐di(tridecan‐7‐yl)anthra[2,1,9‐def:6,5,10‐d'e'f']diisoquinoline‐1,3,8,10(2H,9H)‐tetraone P(DTPDI‐Fc) is designed with ferrocene (Fc) and perylenediimide (PDI) building repeats. The X‐ray diffraction (XRD) test confirms the regioregular stacking styles of P(DTPDI‐Fc) in solid states, and atomic force microscope (AFM) measurement verified the continuous and smooth surface morphology of P(DTPDI‐Fc) films. Therefore, the charge carriers can easily inject into P(DTPDI‐Fc) film and can efficiently migrate throughout P(DTPDI‐Fc) films. Thus, P(DTPDI‐Fc) devices show excellent memory behaviors with low high‐conductance state ON‐state current, stable threshold voltage, long‐time stability, and high device reproducibility. This work affords a practical strategy to weaken molecular stacking defects and to improve stacking regioregularity, which will give a guidance for the designing of multilevel data‐storage ReRAM devices in future researches.

Synthesis, characterization and photophysics of polyplatinaynes based on bis(9,9-dibutyl-2,7-fluorenyl)-2,1,3-benzothiadiazole derivatives

2,1,3-Benzothiadiazole (BT) and its derivatives are very important acceptor units used in the development of photofunctional compounds and are applicable for the molecular construction of organic optoelectronic devices. Due to their strong electron-withdrawing ability, construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials. New organometallic acetylide polymers of platinum(II) bridged by bis(fluorenyl)-benzothiadiazole moiety P1 and P2 have been synthesized via the CuI-catalyzed dehydrohalogenation reaction of the platinum(II) chloride precursors and the corresponding diacetylene ligands. The photophysical, thermal and electrochemical properties of P1 and P2 were investigated.

Preparation of Self‐Assembled Starch‐Based Organometallic Polymers and Their Efficient Adsorption of Mercury Ion in Water

AbstractHerein, a newly‐developed material called Thiourea@WOx/Starch Polymer (TH@WOx/SP) is prepared by a one‐pot and high yield solvothermal method. It is not only equipped with porous structure but also has a superior adsorption capacity. The relevant characterizations and adsorption performance are analyzed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Zeta potential analysis, and differential pulse voltammetry (DPV). Surprisingly, with its abundant active sites, the TH@WOx/SP reveals its excellent adsorption capacity for heavy metal and organics dye, as high as 2201.16 mg g−1 for Hg(II) and 175.01 mg g−1 for methylene blue (MB), finished within 30 and 90 min, respectively. These satisfactorily fast and high adsorption capacities not only come down to its concave–convex structure, but also to its enriched functional groups serving as anchor sites for Hg(II) and MB. The adsorption mechanism of Hg(II) and MB on TH@WOx/SP is carefully evaluated, which can be attributed to covalent coordination, ion exchange, π–π interactions, hydrogen bonds, and electrostatic attraction. This work designs a new strategy to develop a novel porous metal organic polymer adsorbents and demonstrates its prospective application in the field of adsorption.

Growth mechanism of graphite-carbon encapsulated nickel catalysts and curvature effect of carbon layer on the performance of catalytic hydrogenation

This research focuses on the growth mechanism from organometallic coordination polymers precursor to encapsulated catalyst, which contributes to the guiding for the directional design and controlled preparation of the catalyst. Decomposition of organic matter, reduction of nickel, and dissolution/segregation of carbon in the nickel nanoparticles are three main steps for the conversion of Ni@C-OCPs to Ni@C under pyrolysis. The contents of reducing atmosphere during pyrolysis were reduced via selecting organic ligands with smaller molecular and higher C-H ratios. Thus, Ni@C-600 with smaller particle size and larger curvature of the carbon layer surface was obtained. Kinetic experiments showed that it corresponded to a lower apparent activation energy. In addition, density function theory simulation verified that the optimization of the electronic structure generated by the large curvature graphite carbon layer was one of the sources of its excellent activity.

Structure-controlled graphene-encapsulated nickel nanoparticle with tailored work function to steer chemoselective hydrogenation of nitroarenes

In recent years, novel carbon-layer encapsulation strategies have been emerging for the construction of heterogeneous catalysts. However, the mechanism action of thermos-catalytic systems is still unclear. The synergistic effect of metal particle size and carbon layer quantity on catalytic performance has not been reported. The strategy to control the carbon layer quantity and metal particle size is still a big challenge. Here, we proposed a novel idea to design catalysts connecting the performance and the structure via work function. The direct pyrolysis of organometallic coordination polymer is induced to control the carbon layer quantity and metal particle size of the carbon-encapsulated catalyst. The results show that the reduction in the nickel nanoparticle size and the carbon layer quantity were favorable for pumping electrons from the nickel core. There was a corresponding relationship between the work function of the catalyst and its selective hydrogenation performance of halogenated aromatic nitro compounds. With low carbon-halogen bond dissociation energy, a high work function decreased catalytic selectivity. Therefore, the work function can be served as a bridge connecting to the configurational relationship of catalysts.

Direct knitting boosts the stability and catalytic activity of NHC-Au complexes towards valorization of SO2 and CO2

Gold catalysis has been developed rapidly in recent decades, however, the instability of catalysts usually hampered their feasibility in various challenging transformations. Herein, a series of solid porous organometallic polymers (POMPs) were fabricated from N-heterocyclic carbene gold (NHC-Au) complexes via direct knitting strategy. Benefiting from the hierarchical porous structure, single-site and well-preserved catalytic centers of the POMPs, enhanced stability and catalytic activity were achieved in the sulfonylation reaction involving SO2 and carboxylative cyclization involving CO2. Moreover, the solids could be reused for more than 10 runs without obvious loss of activity and selectivity.

Electrically conductive [Fe4S4]-based organometallic polymers.

Tailoring the molecular components of hybrid organic-inorganic materials enables precise control over their electronic properties. Designing electrically conductive coordination materials, e.g. metal-organic frameworks (MOFs), has relied on single-metal nodes because the metal-oxo clusters present in the vast majority of MOFs are not suitable for electrical conduction due to their localized electron orbitals. Therefore, the development of metal-cluster nodes with delocalized bonding would greatly expand the structural and electrochemical tunability of conductive materials. Whereas the cuboidal [Fe4S4] cluster is a ubiquitous cofactor for electron transport in biological systems, few electrically conductive artificial materials employ the [Fe4S4] cluster as a building unit due to the lack of suitable bridging linkers. In this work, we bridge the [Fe4S4] clusters with ditopic N-heterocyclic carbene (NHC) linkers through charge-delocalized Fe-C bonds that enhance electronic communication between the clusters. [Fe4S4Cl2(ditopic NHC)] exhibits a high electrical conductivity of 1 mS cm-1 at 25 °C, surpassing the conductivity of related but less covalent materials. These results highlight that synthetic control over individual bonds is critical to the design of long-range behavior in semiconductors.

Molecular insight into on-surface chemistry of an organometallic polymer.

A molecular investigation of Cu-elimination and subsequent C-C coupling of DCTP (4,4''-dichloro-1,1':3',1''-terphenyl)-Cu organometallic (OM) polymers on Cu(111) is conducted by scanning tunneling microscopy and spectroscopy, revealing that the Cu adatoms embedded in the DCTP-Cu chains are located at the hollow and bridge sites on the Cu(111) surface. The difference in the catalytic activities of these surface sites leads to stepwise elimination of Cu adatoms in the OM chains. Moreover, the interchain interaction plays an important role in the Cu-elimination process of the DCTP-Cu chains as well. The interchain steric hindrance, on the one hand, induces the formation of Cu-eliminated intermediates that are scarcely observed in other Ullmann coupling systems, and on the other hand, promotes the cooperative Cu-elimination and C-C coupling of the OM segments in neighboring chains. These findings demonstrate the key role of the molecule-substrate and intermolecular interactions in mediating the reaction processes of the extended molecular systems on the surface.