Photoresponsive coordination polymers offer precise molecular-to-macroscopic control of mechanical motion, yet their brittleness and limited processability constrain practical implementation. Here we report a hierarchical composite strategy that embeds a one-dimensional Zn(II) coordination polymer capable of topochemical [2+2] cycloaddition within a poly(vinyl alcohol) matrix and coats it with poly(ε-caprolactone), yielding mechanically robust, scalable, and water-stable photomechanical films. The composites exhibit wavelength-selective activation and expansion-programmable deformation, enabling dual-stage bending and radial expansion with actuation fidelity exceeding 98% over extended storage and radial strengths approaching those of load-bearing polymeric systems. Comparative analysis across representative photoactuating materials identifies a distinct regime combining crystalline photochemical precision with macroscopic mechanical resilience. These results establish general design principles-topochemical preorganization, hierarchical stress transfer, and protective coating-for translating lattice-confined photochemistry into durable, expansion-programmable mechanical actuation, providing a foundation for next-generation adaptive and deployable material systems.

We present theoretical investigations of 2D raft-type heterometallic clusters [MMoCp(or C5H4NMe2)(CO)(3)](n) (M = Cu, Ag, Au) with a triangular (n = 3) or square (n = 4) copper, silver, or gold core edge-bridged by three or four metalloligands MoCp(or C5H4NMe2)(CO)(3), respectively (Cp = eta(5)-C5H5; C5H4NMe2 = eta(5)-C5H4NMe2). Various molecular symmetries, C-1, C-s, C-2, D-2, and S-4, were considered, and our calculations reveal an excellent agreement between the most stable computed structures and those determined experimentally by X-ray diffraction when the Cp ligand is used. In contrast, clusters incorporating the C5H4NMe2 ligand display alternative geometries that are energetically more stable than those found experimentally, emphasising the crucial role of the pi-bound ligand on cluster stability. For M = Cu, we demonstrate that square cores with elongated Cu-Cu distances can be stabilised, consistent with previously described systems. Energy decomposition analysis (EDA) at the BP86 level shows that the Cu, Ag, and Au clusters are stabilised by a strong interplay of electrostatic and orbital interactions, with markedly stronger binding in the tetranuclear systems due to cooperative metal-metal and metal-ligand effects. Frontier molecular orbital analysis was used to investigate the electronic structure and potential reactivity of these clusters. The results reveal that metal nature, NMe2 substitution, and cluster nuclearity strongly affect the HOMO-LUMO gaps and charge-transfer behaviour. NMe2-substituted Cu and Au clusters with higher nuclearity display reduced HOMO-LUMO gaps and greater frontier orbital delocalisation, indicating an increased propensity for redox processes. Our theoretical study satisfactorily reproduces the experimental structures of these 2D raft-type heterometallic clusters and highlights the possibility of uncovering new potentially accessible geometries of transition-metal clusters.

This study presents a series of hafnium (Hf1 and Hf2) and zirconium (Zr1 and Zr2) complexes, supported by C,N,N-tridentate, pincer-type ligands, that feature a six-membered metallacycle ortho-fused to a five-membered N,N-chelate. These complexes display remarkable catalytic properties in ethylene homopolymerization, with activities as high as 19,500 kg(PE)mol-1(cat)h-1, producing polyethylenes with impressive molecular weights of up to 1342 kgmol-1. Interestingly, these complexes exhibit an unexpected high selectivity for ethylene in ethylene/1-octene copolymerization, with incorporation levels lower than 0.3 mol %. For comparison, Hf4 with an expanded seven-membered metallacycle has also been synthesized and showed even lower activity. The activation of these metal complexes has been investigated using NMR and MS spectroscopy, revealing that for Hf2 with a six-membered metallacycle, the initial olefin insertion preferentially occurs into the Hf-CAryl bond. In contrast, the ligand in Hf4 is not modified in the presence of the monomer, indicating a different activation pathway associated with the seven-membered metallacyclic structure. Given its high activity and selectivity for ethylene during copolymerization and significant efficiency in chain transfer reactions, Hf2 emerges as a promising candidate for synthesizing hard segments in the production of olefin block copolymers (OBCs) in combination with the conventional C,N,N-Hf complex (py-Hf), whose high melting points (T m s reaching up to 130 degrees C) broaden the potential applications of polyolefin elastomers.

Three-coordinate, paramagnetic CrII complexes of type [Cr(amido)nBnm(NHC)], NHC = N, N'-bis-(2,4,6-trimethylphenyl)-imidazol-2-ylidene (IMes); N, N'-bis-(2,6-di-isopropylphenyl)-imidazol(in)-2-ylidene, (S)IDiPP; N, N'-bis-(2,6-di-isopropylphenyl)-imidazol-4-ylidene, (aIDiPP); amido = N(SiMe3)2, NH(DiPP); Bn = benzyl, n = 2, m = 0; n = 1, m = 1, were prepared by substitution or aminolysis and thermolysis methods from [Cr{N(SiMe3)2}2(THF)2] or [CrBn2((S)IDiPP)], respectively. Depending on the nature of the NHC and the amido ligands, different geometries at CrII (ranging from distorted trigonal planar, to extended Y-, compressed Y-, and distorted T-shaped) and conformations, were observed. HFEPR spectroscopy was employed to accurately determine spin Hamiltonian parameters, consisting of zero-field splitting (axial D and rhombic E components) and g-values, of five S = 2 complexes exhibiting D and E/D in the range from -2.98 to -1.63 cm-1 and 0.026 - 0.069, respectively. AC magnetometry established slow magnetization relaxation in three complexes, operating by Raman or combined Raman-Orbach processes. Ab initio calculations provided computed zfs values, in good agreement with those obtained by HFEPR. Magnetostructural comparisons are made within this three-coordinate CrII family, as well as with previously studied two- or four- coordinate CrII complexes.

Four cis-chelating diphosphanes derived from cyclodextrins (CDs), each featuring a distinct intracavity environment, compel NiII or PdII metal centers to reside within α- or β-CD cavities. Nickel(II) complexes of these metal-confining ligands act as active catalysts in ethylene oligomerization upon activation with modified methylaluminoxane (MMAO). The size of the cavity and the position of the P2Ni fragment relative to the cavity affect both the activity and selectivity of the reaction. In all instances, 1-butene is the major product (up to 98% C4 products and 90% 1-butene within the C4 fraction). Extensive theoretical studies with state-of-the-art methods carried out on the most selective system suggest that the CD cavity restricts isomerization pathways by limiting the mobility of the coordinated olefin in this constrained supramolecular environment, thereby enhancing α-olefin formation.

Photomechanical crystals, capable of transforming light energy into mechanical work, hold significant promise for applications in intelligent actuating devices, artificial muscles, and microrobots, but this calls for more research on the influence of irradiation wavelengths. Here we report a discrete Cd(II)based complex [Cd2(CH2OH-1,3-bpeb)4(3,5-FBA)4] (1; CH2OH-1,3-bpeb = 5-hydroxymethyl-1,3-bis((E)- 2-(pyridin-4-yl)vinyl)benzene, 3,5-FBA = 3,5-difluorobenzoate) which undergoes stepwise [2 + 2] photocycloaddition reactions under visible and ultraviolet light, forming mono-and di-cyclobutane products, respectively, through a single-crystal-to-singlecrystal transformation. This wavelength-controlled process involved the cleavage and subsequent reconstruction of Cd-O bonds within the crystal framework, along with the corresponding lattice contraction and expansion. Those photochemical reactions at different wavelengths initiate various crystal motions, which stem from the stress within the unit cell caused by anisotropic contraction/ expansion. This work opens a new avenue for regulating wavelengths to achieve photocontrolled structural transformations and macroscopic photomechanical motions of molecular crystals.

The concept of photoresponsive coordination polymer (CP) single crystal platforms (CPSCPs) is based on photoresponsive olefin CP single crystals, which can undergo photocycloaddition reactions under light irradiation through a single-crystal-to-single-crystal (SCSC) transformation. Taking advantage of the coordination of olefin ligands to metal ions of Zn2+, Cd2+, etc., a pair of C=C double bonds is positioned adjacent to each other in space at a suitable distance and orientation to allow [2 + 2] photocycloaddition triggered by UV-vis irradiation, affording cyclobutanes in the CPs. The single crystal nature of CPs allows their structures to be determined by X-ray diffraction, providing details of the arrangements in space of the C=C double bonds. These CPs are promising platforms for the synthesis of organic molecules, such as cyclobutanes and derivatives, with high regioselectivity and stereoselectivity without any catalyst. The [2 + 2] photocycloaddition reactions may induce structural modifications like expansion or shrinking of unit cells, resulting in macroscopic changes (e.g., cracking, bending, etc.) of the whole CP single crystals and leading to changes in chemical and physical properties. Applications take advantage of their optical properties, including luminescence and absorption, and allow the detection of guest molecules and photomechanical motions. Although much effort has been devoted to such studies, it remains challenging to develop systematic investigations aiming at increasing the diversity of CPs and properties to meet practical needs. Moreover, more efficient methods are desirable to investigate the reaction mechanisms in the solid state and monitor the structural changes occurring during the process.In this Account, we introduce our research on the design and applications of photoresponsive CPSCPs. It is divided into three parts. First, the design and construction of various CPs with different olefin ligands are discussed. Through a suitable and sometimes sophisticated choice of metal ions and auxiliary carboxylate ligands, these olefin ligands meet the requirements to undergo [2 + 2] photocycloaddition reactions in CP structures, allowing for the precise synthesis of cyclobutanes and their derivatives. These compounds could be subsequently extracted from the CPs to give pure organic products. Second, we introduce new strategies, such as a combination of single crystal X-ray diffraction (SCXRD) with thermal/phototreatments of CPs and in situ fluorescence spectroscopy, to monitor the structural changes occurring on the olefin ligands during the reaction. Furthermore, the fast stepwise photoreaction could also be visualized with high resolution. These data significantly strengthen our understanding of solid-state [2 + 2] photocycloaddition reactions in CPs. Third, applications of photoresponsive CPs are described, which focus on optical and photoinduced mechanical properties. Considering the optical properties, the conjugated structures of the olefin ligands change during the reactions, and circular dichroism (CD) and fluorescence were used for their detection and imaging. Furthermore, the photoinduced mechanical properties of CPs could be significantly expanded through the combination of CP crystals with polymers. Lastly, we point out the challenges and directions for future research in the field. We hope this Account will provide an overview of research on photoresponsive CPSCPs, attract more attention from the community, and inspire future research.

Olefin [2+2] photocycloaddition reactions based on coordination-bond templates provide numerous advantages for the selective synthesis of cyclobutane compounds. This review outlines the recent advances in the design and construction of single crystal platforms of olefinic coordination polymers for precise organic synthesis, in situ exploration of reaction mechanisms, and possible developments as comprehensively as possible. Numerous examples are presented to illustrate how the arrangements of the olefin pairs influence the solid-state photoreactivity and examine the types of cyclobutane products. Furthermore, the photocycloaddition reaction mechanisms are investigated by combining advanced techniques such as single crystal X-ray diffraction, powder X-ray diffraction, nuclear magnetic resonance, infrared spectroscopy, fluorescence spectroscopy, laser scanning confocal microscopy and theoretical calculations. Finally, potential applications resulting from promising physicochemical properties before and after photoreactions are discussed, and existing challenges and possible solutions are also proposed.

Hemilabile ligands are highly promising components of advanced catalysts because their switchable coordination modes can trigger novel activation and stabilization mechanisms. Their increasing use has led to the successful development of stable, active, and selective catalysts. In this study, new aluminum complexes bearing aminoquinoline ligands with different potential hemilabile thiophenyl (Al1), phenoxyl (Al2), or benzyl (Al3) donor arms have been synthesized and used for the ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL). X-ray diffraction analysis revealed that the distance between the Al center and the pendant donor decreased in the order Al3 > Al1 > Al2, consistent with the P-31 NMR spectroscopic evaluations of their relative donor capacities by the Gutmann-Beckett method. ROP of epsilon-CL under otherwise identical conditions revealed that Al1 with a hemilabile thiophenyl donor displayed both higher activity and stability than the complexes with a phenoxyl (Al2) or benzyl (Al3) group. The catalytic properties of the Al complexes were further enhanced by fine-tuning the S substituents. Remarkably, ultrahigh-molecular-weight polycaprolactones (PCLs; M-n up to 41.2 x 10(4) gmol(-1)) were readily synthesized, and immortal catalysis with a catalyst loading as low as 0.01 mol % relative to monomer and a large excess BnOH (up to 100 equiv to Al) was achieved as a result of hemilabile ligand coordination.

Rigid terdentate 'pincer' ligands containing a bridgehead N-heterocyclic carbene (NHC) donor attract considerable interest as spectators in transition metal complexes with broad scope and potential applications in the fields of catalysis, medicinal chemistry and material science. This review aims at compiling and evaluating the developments occurring in the area of complexes with these ligands. The various donor groups in the side-arms that can be associated with the bridgehead NHC donor provide considerable diversity and tunability of the pincer system. In addition to the distinct structural and reactivity features that are discussed in detail, comparisons with related pincer complexes based on all-classical donor sets or mixed donor sets with NHCs at the side-arm(s) only have been undertaken. The review comprises five major sections: the first attempting to differentiate the NHC bridgehead donor as structural element in the pincer ligand design; the following three describing in detail the synthesis, characterization and reactivity of metal complexes with ligand topologies featuring one, two or three NHC donors, respectively; finally the fifth compiling in a tabular format the catalytic applications of the complexes discussed previously, organized as a function of the catalytic reaction, the metal and the ligand type. The review provides a rationally organized coverage of the literature since 2005 in a diverse and fast expanding field dealing with pincer ligand design.

Carbon materials have great potential for applications in energy, biology, and environment due to their excellent chemical and physical properties. Their preparation by carbonization methods encounters limitations and the carbon loss during pyrolysis in the form of gaseous molecules results in low yield of carbon materials. Herein a low-energy (600 °C) and high-yield (82 wt.%) carbonization strategy is developed using liquid gallium-assisted pyrolysis of metal-organic frameworks (MOFs) affording the N-doped carbon nanotube (CNT) non-hollow frameworks encapsulating Co nanoparticles. The liquid gallium layer offers protection against air, promotes heat transfer, and limits the escape of small carbonaceous gaseous molecules, which greatly improve the yields of the pyrolysis reaction. Experimental and theoretical results reveal that the synergistic interaction between CNTs and N/O-containing groups gives a non-hollow framework composed of N/O-enriched and open CNTs (NOCNTF-15, 15 denotes the 15 mm thickness of the liquid gallium layer during the pyrolysis) with high specific capacity (185 mAh g-1 at 10 A g-1) and ultra-stable cyclability (stable operation at 10 A g-1 and 50 °C for 20 000 cycles). This study provides a unique approach to carbonization that facilitates the practical application of low-cost CNTs and other MOFs-derived carbon materials in high-performance sodium-ion batteries (SIBs).

Controlling the packing of olefinic molecules in crystals is essential for triggering solid-state [2 + 2] photocycloaddition reactions and the synthesis of photocontrolled smart materials. Herein, we report the stepwise photodimerization-triggered photopolymerization of two triene coordination polymers (CPs), {[Zn(2-BBA)2(tpeb)]·0.5CH3CN}n (1, 2-HBBA = 2-bromobenzoic acid, tpeb = 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene) and {[Zn(3-BBA)2(tpeb)]·CH3CN)}n (2, 3-HBBA = 3-bromobenzoic acid). Upon irradiation with 420 nm light, each pair of closely packed and parallel olefinic bonds in 1 undergoes a [2 + 2] cycloaddition reaction, which connects two adjacent Z-shaped chains into a ladder-like coordination chain [Zn(2-BBA)2(bpbdpvpcb)0.5]n (1a, bpbdpvpcb = 1,3-bis(4-pyridyl)-2,4-bis(3,5-di(2-(4-pyridyl)vinyl)phenyl]cyclobutene) through single-crystal to single-crystal (SCSC) transformation. After photodimerization from 1 to 1a has occurred, the olefinic bonds that were initially distant are brought in close enough proximity to meet the requirements for a subsequent [2 + 2] cycloaddition reaction. Upon further light irradiation, the neighboring bpbdpvpcb ligands in 1a experience a SCSC photopolymerization based on [2 + 2] photocycloaddition and transform into poly-3b,4,5,5a,8b,9,10a-octahydro-4,5,9,10-tetrapyridyl-2,7-di(2-(4-pyridyl)vinyl)dicyclobuta[e,l]-pyren (poly-otpdpvdcbp). 2 showed similar structural changes under UV light illumination. Under light exposure, single crystals of 1 and 2 with different morphologies exhibit bending, cracking, and jumping photomechanical motions. The composite film (1-PVA) engineered by dispersing crystalline particles of 1 in poly(vinyl alcohol) (PVA) displays interesting light-wavelength-dependent photomechanical motions and can perform photodriven swimming on a liquid surface. This work provides a useful and promising approach to enable photodimerization of those photoinactive olefin pairs embedded in CPs and opens a new route to synthesize organic polymers by using olefinic CP platforms.

When aiming at the direct use of CO2 for the preparation of advanced/value-added materials, the synthesis of CO2/olefin copolymers is very appealing but challenging. The δ-lactone 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP), synthesized by telomerization of CO2 with 1,3-butadiene, is a promising intermediate. However, chemoselective ring-opening polymerization (ROP) of EVP is hampered by unfavorable thermodynamics and the competitive polymerization of highly reactive C=C double bonds. Herein, we report the first chemoselective ROP of EVP using a phosphazene/urea binary catalyst, affording exclusively a linear unsaturated polyester poly(EVP)ROP, with a molar mass (Mn) up to 6.5 kg·mol-1 and narrow distribution (Ð = 1.24), which can be fully recycled back to the pristine monomer, thus establishing a monomer-polymer-monomer closed-loop life cycle. Remarkably, poly(EVP)ROP features two pendent C=C double bonds per repeating unit, which show distinct reactivity and thus can be properly engaged in sequential functionalizations towards the synthesis of bifunctional polyesters. This methodology provides a facile access to bifunctional and recyclable polyesters from readily available feedstocks. In these polyesters, the carbon dioxide content reaches 33 mol% (29 wt%). The reasons for the remarkable chemoselectivity observed were investigated by Density-functional theory (DFT) calculations.

Critical review of four new volumes in the book series “Series on Chemistry, Energy and the Environment” (World Scientific Publishing, Singapore): Synthesis and Applications in Chemistry and Materials, 4 volumes, 2100 pages (March 2024). https://doi.org/10.1142/13309.Volume 11: Metal Coordination and NanomaterialsVolume 12: Enzymatic and Organic SystemsVolume 13: Metal Complex Catalytic Systems and MaterialsVolume 14: Biomass and Waste Valorisation, Functional Materials, Energy Conversion and Supercritical SystemsThese volumes were edited by Armando J. L. Pombeiro (Universidade de Lisboa, Portugal), Kamran T. Mahmudov (Universidade de Lisboa, Portugal) and M. Fátima C. Guedes da Silva (Universidade de Lisboa, Portugal).

Zwitterionic thiolate ligands have the potential to introduce novel assembly modes and functions for noble metal clusters. However, their utilization in the synthesis of silver clusters remains understudied, particularly for the clusters containing reductive Ag(0) species. In this article, we report the first synthesis of a mixed-valence silver(0/I) cluster protected by zwitterionic Tab as thiolate ligands (Tab = 4-(trimethylammonio)benzenethiolate), denoted as [Ag-22(Tab)(24)](PF6)(20)16CH(3)OH6Et(2)O (Ag-2216CH(3)OH6Et(2)O), alongside an Ag(I) cluster [Ag-20(Tab)(12)(PhCOO)(10)(MeCN)(2)(H2O)](PF6)(10)11MeCN (Ag-2011MeCN). Ag-22 has a distinct hierarchical supratetrahedral structure with a central {Ag-6} kernel surrounded by four [Ag-4(Tab)(6)](4+) units. High-resolution electrospray ionization mass spectra demonstrate that Ag-22 has two free electrons, indicating a superatomic core. Ag-20 has a drum-like [Ag-12(Tab)(6)(PhCOO)(6)(H2O)](6+) inner core capped by two tetrahedral-like [Ag-4(Tab)(3)(PhCOO)(2)(MeCN)](2+) units. Ag-20 can be transformed into Ag-22 after its reaction with NaBH4 in solution. Antibacterial measurements reveal that Ag-22 has a significantly lower minimum inhibitory concentration than that of the Ag-20 cluster. This work not only extends the stabilization of silver(0/I) clusters to neutral thiol ligands but also offers new materials for the development of novel antibacterial materials.

The pincer complexes [NiIIBr(CNC)]Br (4), [CrIIIBr3(CNC)] (5 a) and [CrIIIBr2.3Cl0.7(CNC)] (5 b), where CNC=3,3'-(pyridine-2,6-diyl)bis(1-mesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene), were obtained from the novel ligand CNC, generated in situ from the precursor (CHNCH)Br2 and [NiIIBr2(PPh3)2] or from [CrII{N(SiMe3)2}2(THF)2] and (CHNCH)Br2 by aminolysis, respectively. The tetrahedrally distorted square planar (τ4≅0.30) geometry and the singlet ground state of Ni in 4 were attributed to steric constraints of the CNC backbone. Computational methods highlighted the dependence of the coordination geometry and the singlet-triplet energy difference on the size of the N-substituent of the tetrahydropyrimidine wingtips and contrasted it to the situation in 5-membered imidazolin-2-ylidene pincer analogues. The octahedral CrIII metal center in 5 a and 5 b is presumably formed after one electron oxidation from CH2Cl2. 4/MAO and 5 a/MAO were catalysts of moderate activity for the oligomerization and polymerization of ethylene, respectively. The analogous (CH^N^CH)Br2 precursor, where (CH^N^CH)=3,3'-(pyridine-2,6-diylbis(methylene))bis(1-mesityl-3,4,5,6-tetrahydropyrimidin-1-ium), was also prepared, however its coordination chemistry was not studied due to the inherent instability of the resulting free C^N^C ligand.

Deuteration of amine compounds has been widely of concern because of its practical role in organic reaction mechanisms and drug research; however, only limited deuteration label methods are accessible with D2O as a deuterium source. Herein, we propose a convenient deuteration protocol, including preparing D2 by the AlGa activation method, using PtRu nanowires as catalysts, and utilizing the elementary step in the couple reaction involving an imine unit, to realize the rapid preparation of a secondary amine with a diversified deuteration label. The self-coupling between nitriles not only provides a symmetric secondary amine with four α-D atoms but also produces high-valued ND3 in an atomic-economic way.