Extra Coordination Research Articles

Realizing Dual-Mode Zinc-Ion Storage of Generic Vanadium-Based Cathodes via Organic Molecule Intercalation.

Intercalation engineering is a promising strategy to promote zinc-ion storage of layered cathodes; however, is impeded by the complex fabrication routes and inert electrochemical behaviors of intercalators. Herein, an organic imidazole intercalation strategy is proposed, where V2O5 and NH4V3O8 (NVO) model materials are adopted to verify the feasibility of the imidazole intercalator in improving the zinc storage capabilities of vanadium-based cathodes. The intercalated imidazole molecules could not only expand interlayer spacing and strengthen structural stability by serving as extra "pillars" but also provide extra coordination sites for zinc storage via the coordination reaction between Zn2+ and the C═N group. This gives rise to a dual-mode ion storage mechanism and favorable electrochemical performances. As a result, imidazole-intercalated V2O5 delivers a capacity of 179.9 mAh g-1 after 5000 cycles at 20 A g-1, while the imidazole-intercalated NVO harvests a high capacity output of 170.2 mAh g-1 after 700 cycles at 2 A g-1. This work is anticipated to boost the application potentials of vanadium-based cathodes in aqueous zinc-ion batteries.

Six‐Membered Ring Directed Assembly of a Zirconium Zeolitic Metal–Organic Framework for Efficient Separation of Hexane Isomers

AbstractThe synthesis of zirconium MOFs with zeolite net is quite challenging due to the high connectivity of Zr6 clusters, which is far from tetrahedral connection, a requisite for zeolite net. In this work, we demonstrate a six‐membered ring (6MR) strategy through mimicking of mineral zeolites with mixed ditopic and tritopic carboxylate linkers. With this strategy, the ditopic linker cross‐links Zr6 clusters to form 4‐connected zeolite‐like nets, while the tritopic one is used to direct the formation of 6MR and simultaneously consumes extra coordination sites on the cluster. The feasibility of this strategy is shown by one zeolitic metal–organic framework (NNM‐5) and this strategy has also led to the synthesis of the other dia‐type zirconium MOF (NNM‐6). Interestingly, as the tritopic linker not only directs the formation of 6MR but also partitions 6MR into small segments, NNM‐5 with SOD topology shows a structural feature of small aperture and big cage, which has led to efficient separation of hexane isomers. With both exceptionally high n‐hexane uptake (65.9 cm3 g−1) and size‐exclusion selectivity, an exceptional separation capability is verified by breakthrough experiments. Calculation results demonstrate that the large difference of diffusion energy barrier due to the small aperture accounts for the underlying separation mechanism.

Six-Membered Ring Directed Assembly of a Zirconium Zeolitic Metal-Organic Framework for Efficient Separation of Hexane Isomers.

The synthesis of zirconium MOFs with zeolite net is quite challenging due to the high connectivity of Zr6 clusters, which is far from tetrahedral connection, a requisite for zeolite net. In this work, we demonstrate a six-membered ring (6MR) strategy through mimicking of mineral zeolites with mixed ditopic and tritopic carboxylate linkers. With this strategy, the ditopic linker cross-links Zr6 clusters to form 4-connected zeolite-like nets, while the tritopic one is used to direct the formation of 6MR and simultaneously consumes extra coordination sites on the cluster. The feasibility of this strategy is shown by one zeolitic metal-organic framework (NNM-5) and this strategy has also led to the synthesis of the other dia-type zirconium MOF (NNM-6). Interestingly, as the tritopic linker not only directs the formation of 6MR but also partitions 6MR into small segments, NNM-5 with SOD topology shows a structural feature of small aperture and big cage, which has led to efficient separation of hexane isomers. With both exceptionally high n-hexane uptake (65.9 cm3 g-1) and size-exclusion selectivity, an exceptional separation capability is verified by breakthrough experiments. Calculation results demonstrate that the large difference of diffusion energy barrier due to the small aperture accounts for the underlying separation mechanism.

The interpersonal coordination constraint on the volleyball setter’s decision-making on setting direction

This study investigated the setter’s decision-making on setting direction based on interpersonal (interaction between players) and extra personal (interaction between players and some place or object) coordination. The sample consisted of 86 sequences of play involving settings performed by males (n = 43) and females (n = 43). Fifty-nine spatiotemporal measures of interpersonal and extra personal coordination were obtained from the x and y coordinates of volleyball players’ displacements using the TACTO software. Settings to each court zone were compared in relation to each spatiotemporal measure. Results showed that when the final area between attacker in the zone 3 and block was greatest and emerged from highest velocity, setters decided to set to zone 2. On the other hand, when the foregoing area was smallest and emerged from lowest velocity, setters decided to set to zones 3 and 4. It was concluded that the final area between attacker in the zone 3 and block and its emerging velocity constrained the setters’ decision-making on setting direction. This study provides useful insights into the design of practice tasks in volleyball, suggesting that setters should be advised to be attuned to the interpersonal coordination involving attacker in the zone 3 and block.

Stoichiometry-controlled chirality inversion in the amide-linked zinc bisporphyrinates induced by amino acid esters

We investigated chirality transfer processes with two amide-linked zinc bisporphyrinates as hosts and chiral amino acid esters as guests. The linkers in these hosts contain a coordination site (pyridyl nitrogen or amino nitrogen). CD spectra were measured after titration of these zinc bisporphyrinates with amino acid esters. The CD spectra show that the signals were inverted during the titration. This result suggests that there is a two-step chirality induction process, which is most likely dominated by the corresponding 1:1 and 1:2 host-guest complexes. In the 1:1 complexes, the pyridyl nitrogen or amino nitrogen in the linkers is coordinated with zinc. NMR spectra confirmed such coordination interactions. Theoretical calculations also confirmed the corresponding chirality induction and inversion. This work provides a useful strategy to tune chirality transfer processes by introducing an extra coordination site in the linker.

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N 5 Site for Enhanced Electrocatalytic Reaction

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N ₅ Site for Enhanced Electrocatalytic Reaction

Solvent Effect on Film Formation and Trap States of Two-Dimensional Dion-Jacobson Perovskite.

Two dimensional Dion-Jacobson (2D DJ) perovskite has emerged as a potential photovoltaic material because of its unique optoelectronic characteristics. However, due to its low structural flexibility and high formation energy, extra assistance is needed during crystallization. Herein, we study the solvent effect on film formation and trap states of 2D DJ perovskite. It is found that the nucleation process of 2D DJ perovskite can be retarded by extra coordination, which is proved by in situ optical spectra. As a benefit, out-of-plane oriented crystallization and ordered phase distribution are realized. Finally, in 1,5-pentanediammonium (PeDA) based 2D DJ perovskite solar cells (PSCs), one of the highest reported open-circuit voltage (VOC) values of 1.25 V with state-of-the-art efficiency of 18.41% is obtained due to greatly shallowed trap states and suppressed nonradiative recombination. The device also exhibits excellent heat tolerance, which maintains 80% of its initial efficiency after being kept under 85 °C after 3000 h.

Tuning the Interaction between Ruthenium Single Atoms and the Second Coordination Sphere for Efficient Nitrogen Photofixation

AbstractOrienting the migration of photogenerated electrons to the target active single atoms instead of dissipation at inert sites is crucial to improve the photocatalytic activity of single‐atom catalysts, but remains a challenge. Herein, it is demonstrated that the strong interaction between Ru single atoms and the second coordination sphere significantly enriches photogenerated electrons at Ru active sites and boosted N2 photofixation activity. The extra RuCo coordination from the strong interaction with the second coordination sphere is observed over CoO‐supported Ru single atoms (RuO+Co/CoO) relative to the weakly interacting ones (RuO/CoO). For N2 photofixation, RuO+Co/CoO exhibits an ammonia production rate of 306 µmol gcat.−1 h−1 without any sacrificial agents at room temperature, which is 4.6 times that of RuO/CoO. Mechanistic studies reveal that RuCo coordination in RuO+Co/CoO serves as an additional photoelectron transfer channel. Such channel promotes the accumulation of photoelectrons that excite from O to Co atoms on Ru active sites, facilitating the photoreduction of N2 into NH3 process. The concept of the second coordination sphere modulation offers a powerful platform toward rational design of highly efficient single‐atom catalysts for N2 fixation and beyond.

Pt–Cu Interaction Induced Construction of Single Pt Sites for Synchronous Electron Capture and Transfer in Photocatalysis

AbstractSingle‐atom photocatalysts have shown their fascinating strengths in enhancing charge transfer dynamics; however, rationally designing coordination sites by metal doping to stabilize isolated atoms is still challenging. Here, a one‐unit‐cell ZnIn2S4 (ZIS) nanosheet with abundant Cu dopants serving as the suitable support to achieve a single atom Pt catalyst (Pt1/Cu–ZIS) is reported, and hence the metal single atom–metal dopant interaction at an atomic level is disclosed. Experimental results and density functional theory calculations highlight the unique stabilizing effect (Pt–Cu interaction) of single Pt atoms in Cu‐doped ZIS, while apparent Pt clusters are observed in pristine ZIS. Specifically, Pt–Cu interaction provides an extra coordination site except three S sites on the surface, which induces a higher diffusion barrier and makes the single atom more stable on the surface. Apart from stabilizing Pt single atoms, Pt–Cu interaction also serves as the efficient channel to transfer electrons from Cu trap states to Pt active sites, thereby enhancing the charge separation and transfer efficiency. Remarkably, the Pt1/Cu–ZIS exhibits a superb activity, giving a photocatalytic hydrogen evolution rate of 5.02 mmol g−1 h−1, nearly 49 times higher than that of pristine ZIS.

Synthesis, structure and magnetic properties of an oxamate-based 1D coordination polymer built on pentametallic links

The solvothermal reaction of the hexadentate 2-(oxamato)benzoic acid ligand (oaba) with copper(II) and cobalt(II) ions has yielded the [Cu4Co3(oaba)4(OH)2(DMF)6]·2(DMF)·1H2O (1) 1D coordination polymer. The single-crystal X-ray diffraction study reveals the formation of a neutral chain built from pentametallic complexes where each multi-polydentate ligand bridges four metal centres. The atypical morphology observed here for an oxamate-based 1D polymer arises from the use of a ligand bearing extra coordination sites. Magnetometry indicates strong dominating antiferromagnetic interactions within the polymer resulting in a non-zero ferrimagnetic state at low temperature.

Precise Spin Manipulation of Single Molecule Positioning on Graphene by Coordination Chemistry.

Precise spin manipulation of single molecules is crucial for future molecular spintronics. However, it has been a formidable challenge due to the complexities of the strong molecule-substrate coupling as well as the response of the molecule to external stimulus. Here we demonstrate by density functional theory calculations that precise spin manipulation can be achieved by extra CO and NO molecules coordination to transition metal phthalocyanine (TMPc) (TM = Co, Fe, Mn) molecules deposited on metal-supported graphene; the spins of TMPc molecules are switched from S to S - 1/2 (|S - 1|) after NO (CO) coordination. With the aid of a combination of molecular orbitals (MO) theory and recently developed principal interacting spin-orbital (PISO) analysis, the impacts of NO and CO coordinations on both adsorption configuration and spin polarization of TMPc are well elucidated. We reveal the different coordination geometries that CO always coordinates axially to the TM center with a linear geometry, while NO prefers a bent geometry, which can be attributed to the competition between the σ- and π-type interactions according to the PISO analysis. Particularly, the NO-MnPc complex adopts a bent geometry deviating from the prediction by the existing Enemark-Feltham formalism. In addition, MO analysis suggests that during the CO coordination, the simultaneous existence of σ-donation and π-back-donation promotes electrons flowing from the dz2 to partially occupied dπ (dxz and dxz) orbitals with subsequent reordering of the TM d-orbitals, resulting in the spin transition of S → |S - 1|. In comparison, given that NO is regarded as NO- when it adopts a bent geometry coordinating to the TM center, the complete (CoPc) or partial (FePc and MnPc) quenching of the molecular spins caused by NO coordination is attributed to the electron transfer from TM to NO. These theoretical findings provide important insights into relevant experiments and offer an effective design strategy to realize underlying single-molecular spintronics devices integrated with two-dimensional materials.

Cathecol and Naphtol Groups in Salphen-Type Schiff Bases for the Preparation of Polynuclear Complexes.

In this paper, we show a strategy to modify salphen-type Schiff base ligands with naphtol (SYML1) and pyrocathecol (2,3-dihydroxyphenyl) groups (SYML2), or a combination of both (ASYML). Each of these ligands can be used to obtain polynuclear metal complexes following two different strategies. One relies on using metals that are either too large for the N2O2 cavity or not fond of coordination number 4 and the other one relies on forcing the polynuclear species by adding functional groups to the hydroxybenzaldehayde in order to have extra coordination sites in the ligand. We report and characterize the mononuclear complexes SYML1-Cu and SYML1-Ce, along with the dinuclear complex SYML1-Fe and the tetranuclear species SYML2-Mn. The asymmetric ligand ASYML routinely hydrolyzes into the symmetric ligands in the reaction mixtures. SYML1-Fe displays a nearly linear Fe-O-Fe bridge with very strong antiferromagnetic coupling between the Fe(III) ions.

A new series of three-coordinate cuprous complexes formed by steric hindrance of a phosphine ligand: Synthesis, structure characterization, properties and TD-DFT calculations

Four new three-coordinate cuprous complexes with a CuN2P core, 1-QBO, 2-Phen, 3-MePBO, 4-QBI, were designed and synthesized by utilizing a steric hindrance of phosphine ligand o-Anisyl3P [QBO = 2-(2′-quinolyl)benzoxazole, Phen = 1,10-Phenanthroline, MePBO = 5-methyl-2-(2′-pyridyl)-benzoxazole, QBI = 2-(2′-quinolyl)benzimidazole, o-Anisyl3P = tri(2-methoxyphenyl)-phosphine]. As a counterpart to 1-QBO, a four-coordinate complex 5-QBOP2 has also been synthesized with a CuN2P2 core. All complexes were characterized by single-crystal X-ray diffraction, spectroscopic analysis (IR, UV–Vis), elemental analysis, and photoluminescence study. Single-crystal X-ray diffraction revealed that complexes 1–4 all adopt trigonal CuN2P coordination geometry with one phosphine and one diimine ligand. Their UV–Vis absorption spectra exhibit concentration dependences of absorption edge shift. Time-dependent density functional theory (TD-DFT) calculations reveal that their S1 states and the peak transition states can be mainly assigned as ligand–ligand & metal–ligand charge transfer (L′LCT + MLCT) and intra-ligand charge transfer (ILCT) states, respectively. It is noteworthy that all three-coordinate complexes 1–4 do not display obvious photoluminescence (PL), whereas the PL of four-coordinate complex 5 is turned on by an extra coordination of a phosphine ligand to 1. This PL complex has also been synthesized and characterized as 5-QBOP2 from 1-QBO. This model of three-coordinate to four-coordinate change with PL turn-on behavior could be used for sensing volatile organic compounds (VOCs).

Strontium ion substituted alginate‐based hydrogel fibers and its coordination binding model

ABSTRACTSr‐alginate and Ca‐alginate hydrogel fibers were fabricated via microfluidic spinning technology, and various analytical methods were adopted to characterize fibers and disclose the coordination model of Sr2+ binding with alginate molecule chain. For both fibers, the more crosslinking sites of Sr2+ with alginate molecule were illustrated in comparison with that of Ca2+. The more robust mechanical performance of Sr‐alginate fibers than Ca‐alginate counterpart was a strong indication of the more strong binding of Sr2+ with alginate molecular chain. FTIR and electric conductivity disclosed the chelation type of Sr2+ with alginate macromolecule being similar to that of Ca2+, which was core‐shell of the analogous “egg‐box” structure. Circular dichroism spectroscopy further certified the extra coordination sites for Sr2+ with alginate molecule than Ca2+. Research on the coordination model will be more beneficial to optimizing the physicochemical properties of alginate fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48571.

Investigating the evolving context of an unstable approach in aviation from mental model disconnects with an agent-based model

Unstable approach is an adverse aviation event, and it is strongly related to the interaction between pilots and air traffic controllers (ATCOs). Mental model disconnects among team members can be a major cause of possible interaction conflicts and defective team cognition. Therefore, to study the negative effects of various mental model disconnects, a framework of evolving team cognition (FETC) is proposed to examine the evolving context of an accident. An agent-based model (ABM) is developed to simulate how mental model disconnects are involved in evolving landing scenarios. The results of a simulation conducted with the ABM indicate that mental model disconnects occur more frequently as an aircraft approaches the terminal area. For landing scenarios in the outer area between 100 and 50 nautical miles (Nm), task-related mental model disconnects occur more frequently, causing incompatibility between parties. The incompatibility reveals the necessity of extra coordination to prevent the potential occurrence of system errors. As for the scenarios around the terminal area (30–15 Nm), the team-related mental model disconnects prevail, leading to passive information dissemination regarding changing conditions and late initiation of urgent coordination. The combination of these factors causes a team to miss the window for preventing an adverse event.

Electronic and magnetic properties of CoPc and FePc molecules on graphene: the substrate, defect, and hydrogen adsorption effects.

Transition metal phthalocyanines (TMPcs) are particularly appealing for spintronic processing and data storage devices due to their structural simplicity and functional flexibility. To realize effective control of the spins in TMPc-based systems, it is necessary to quantify how the structural and chemical environment of the molecule affects its spin center. Herein we perform a detailed investigation of the electronic and spintronic properties of vertically stacked heterostructures formed by CoPc or FePc adsorbed on a monolayer of graphene under the influences of the gold substrate, vacancies in graphene, and extra atomic hydrogen coordination on the TMPc. By using density functional theory (DFT), we reveal that both the TMPc molecules prefer the carbon-top position on graphene, and the existence of the Au substrate enhances the stability of the adsorption, while this enhanced adsorption will not modify the molecular magnetism, keeping it the same value as in the free standing case. Moreover, with the aid of a combination of DFT and ab initio wavefunction-based calculations, our results indicate that the magnetic anisotropy of the FePc-graphene complex can be actively tuned by the Au substrate. Our calculations also show that defects in graphene including single and double vacancies can modify the magnetism of these heterostructures. In particular, the spin state of FePc can be tuned from S = 1 to S = 2 with such defect engineering. Further spin state tunability can be achieved from a hydrogenation process, with the coordination of one extra hydrogen on the Co-top site for CoPc and the pyridinic N site for FePc, respectively, tuning their spin states from S = 1/2 to S = 0 and from S = 1 to S = 2. These findings may prove to be instrumental for rational design of future molecular spintronics devices integrated with two-dimensional materials.

Induced Aggregation and Synergistic Coordination Strategy in Cluster Organic Architectures.

Developments in strategies for the synthesis of oxo-hydroxo lanthanide (Ln) clusters during the past few decades have resulted in abundant relevant crystalline materials that exhibit attractive structures and interesting properties. The combination of these oxo-hydroxo Ln clusters and organic ligands has led to the formation of new extended arrays of Ln cluster organic frameworks (LnCOFs). In contrast to metal-organic frameworks, the incorporation of particular characteristics of clusters provides the opportunity to develop performances not available in single-metal compounds. Even with steady advances in oxo-hydroxo Ln clusters, progress in LnCOFs is less developed. To obtain LnCOFs, one premise is to induce the oxophilic Ln ions undergoing aggregation. Meanwhile, the organic ligands should have extra coordination sites for further expansion. Multidentate organic ligands like pyrazinecarboxylic acid and pyridinecarboxylic acid containing O and N donors will meet these two requirements. Their carboxyl groups will induce the aggregation of Ln ions, while the N donors can serve as potential extension sites. To make more open frameworks or if the oxo-hydroxo Ln clusters fail to be congregated or connected, then a second ligand is necessary. The introduction of the suitable second ligand may occupy a partial coordination sphere of Ln ions and ultimately benefit the connection process. In this Account, we introduce the origin and evolution of the induced aggregation and synergistic coordination strategy. According to the attributes of the organic ligands in the documented LnCOFs, we classify them into linear and nonlinear groups in the second and third parts. From the aspect of ligand-induced aggregation, isonicotinic acid (HIN) and lengthened 4-(4-pyridyl)benzoic acid (HPBA) ligands as well as their nonlinear analogues are settled as typical models. From the aspect of synergistic coordination, chelating ligands like 1,2-benzenedicarboxylic acid (1,2-H2BDC) and acetic acid (HOAc) play significant roles. Moreover, three types of synergistic coordination are discussed in detail: synergistic coordination between two types of organic ligands, synergistic coordination between organic and inorganic ligands, and simultaneous synergistic coordination of aforementioned two types. From the aspect of LnCOF products, in addition to traditional pure LnCOFs, new types of heterometallic frameworks containing two types of cluster building units have been developed. Although this Account focuses on the nuclearity and coordination aspects of LnCOFs, we anticipate that it will stimulate more efforts in the further study of their properties beyond the exploratory synthesis. More importantly, synergistic coordination may be applied to other systems and inspire crystal design and targeted assembly of new functional materials.

Cu(II) ion directed self-assembly of a Y8/Cu6 heterometallic coordination cage via an Y(III) metalloligand

A non-centrosymmetric yttrium [Y(III)] metalloligand, [Y(H3L)(NO3)]·2NO3·THF (1) {tris{[2-{(imidazole)methylidene}amino]-ethyl}amine = H3L}, was synthesized and subsequently used in a Cu(II) directed self-assembly process to form a Y8/Cu6- type heterometallic coordination cage [Cu6Y8L8(NO3)5(H2O)3]·7NO3·21H2O (2). The eight corners of the distorted cubic cage are defined by eight Y(III) ions while Cu(II) ions occupy the centers of six faces with two opposite Cu(II) ions considerably outside the faces. The asymmetric Y(III) metal centres due to the extra coordination of either water molecules or nitrate anions induce chirality in the cage, with equal numbers of both enantiomers present in the solid state. The cage formation in both solution and in the solid state was demonstrated by ESI-MS and single crystal X-ray diffraction. Magnetic property measurements indicate that cage 2 remains paramagnetic down to 2 K. In addition, vibrational modes, electronic structure and thermal stability of the coordination cage 2 have been further investigated and reported.

Polyphenylcyclopentadienyl Ligands as an Effective Light-Harvesting π-Bonded Antenna for Lanthanide +3 Ions.

A new approach to design "antenna-ligands" to enhance the photoluminescence of lanthanide coordination compounds has been developed based on a π-type ligand-the polyphenyl-substituted cyclopentadienyl. The complexes of di-, tri-, and tetraphenyl cyclopentadienyl ligands with Tb and Gd have been synthesized and all the possible structural types from mononuclear to di- and tetranuclear complexes, as well as a coordination polymer were obtained. All types of the complexes have been studied by single-crystal X-ray diffraction and optical spectroscopy. All terbium complexes are luminescent at ambient temperature and two of them have relatively high quantum yields (50 and 60%). Analysis of energy transfer process has been performed and supported by quantum chemical calculations. The role of a low-lying intraligand charge transfer state formed by extra coordination with K+ in the Tb3+ ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes containing π-type ligands with desired luminescence properties have been proposed.

Dimeric and Trimeric Supramolecular Systems Formed by Donor‒Acceptor Interactions of ZnII, MnIII, and SnIV Porphyrin Complexes

The paper presents the methods of synthesis of dimeric and trimeric compounds formed by donor–acceptor interactions of ZnII, MnIII, and SnIV porphyrin complexes. The structure of the porphyrin ensembles was determined by 1H NMR spectroscopy. The extra coordination properties of the synthesized dimeric and trimeric supramolecular systems in relation to nitrogen-containing compounds were studied and the stability constants of the resulting porphyrin extra complexes were determined.