Organic Bridging Ligands Research Articles

Proton-conductive properties of a stable three-dimensional aluminum(III)-organic framework constructed by porphyrinlcarboxylate

The proton conductivity (σ) of the highly stable metal-organic frameworks (MOFs) built by carboxylic acid ligand and aluminum metal has not been fully investigated. Herein, a three-dimensional aluminum-based MOF, [(AlOH)2TCPP]n (namely Al-TCPP) with exceptional structural stability was solvothermally synthesized using an organic multifunctional bridging ligand, meso-tetra(4-carboxyphenyl)porphine (H4TCPP) with a large stiff ring structure and Al(NO3)3⋅9H2O as raw materials. The dependency of σ on temperature and relative humidity (RH) was surveyed using the AC impedance test after the MOF's thermal, water, and chemical stabilities, as well as nitrogen and H2O vapor adsorptions, were all characterized. Experimental results demonstrated that this highly stable MOF with a high specific surface area exhibited impressive proton conductivity, with an optimal σ of 3.2 × 10-4 S/cm under 100 °C/98% RH. Furthermore, the proton-conducting mechanism inside the framework was highlighted using computed activation energy and structural analysis. This study provides new inspiration for designing and searching for high-performance proton-conductive materials.

Recent Advances in Metal-Organic Framework (MOF)-Based Composites for Organic Effluent Remediation.

Environmental pollution caused by organic effluents emitted by industry has become a worldwide issue and poses a serious threat to the public and the ecosystem. Metal-organic frameworks (MOFs), comprising metal-containing clusters and organic bridging ligands, are porous and crystalline materials, possessing fascinating shape and size-dependent properties such as high surface area, abundant active sites, well-defined crystal morphologies, and huge potential for surface functionalization. To date, numerous well designated MOFs have emerged as critical functional materials to solve the growing challenges associated with water environmental issues. Here we present the recent progress of MOF-based materials and their applications in the treatment of organic effluents. Firstly, several traditional and emerging synthesis strategies for MOF composites are introduced. Then, the structural and functional regulations of MOF composites are presented and analyzed. Finally, typical applications of MOF-based materials in treating organic effluents, including chemical, pharmaceutical, textile, and agricultural wastewaters are summarized. Overall, this review is anticipated to tailor design and regulation of MOF-based functional materials for boosting the performance of organic effluent remediation.

Regulated Dual Defects of Bridging Organic and Terminal Inorganic Ligands in Iron-based Metal-Organic Framework Nodes for Efficient Photocatalytic Ammonia Synthesis.

Engineering advantageous defects to construct well-defined active sites in catalysts is promising but challenging to achieve efficient photocatalytic NH3 synthesis from N2 and H2O due to the chemical inertness of N2 molecule. Here, we report defective Fe-based metal-organic framework (MOF) photocatalysts via a non-thermal plasma-assisted synthesis strategy, where their NH3 production capability is synergistically regulated by two types of defects, namely, bridging organic ligands and terminal inorganic ligands (OH- and H2O). Specially, the optimized MIL-100(Fe) catalysts, where there are only terminal inorganic ligand defects and coexistence of dual defects, exhibit the respective 1.7- and 7.7-fold activity enhancement comparable to the pristine catalyst under visible light irradiation. As revealed by experimental and theoretical calculation results, the dual defects in the catalyst induce the formation of abundant and highly accessible coordinatively unsaturated Fe active sites and synergistically optimize their geometric and electronic structures, which favors the injection of more d-orbital electrons in Fe sites into the N2 π* antibonding orbital to achieve N2 activation and the formation of a key intermediate *NNH in the reaction. This work provides a guidance on the rational design and accurate construction of porous catalysts with precise defective structures for high-performance activation of catalytic molecules.

Regulated Dual Defects of Bridging Organic and Terminal Inorganic Ligands in Iron‐based Metal‐Organic Framework Nodes for Efficient Photocatalytic Ammonia Synthesis

AbstractEngineering advantageous defects to construct well‐defined active sites in catalysts is promising but challenging to achieve efficient photocatalytic NH3 synthesis from N2 and H2O due to the chemical inertness of N2 molecule. Here, we report defective Fe‐based metal‐organic framework (MOF) photocatalysts via a non‐thermal plasma‐assisted synthesis strategy, where their NH3 production capability is synergistically regulated by two types of defects, namely, bridging organic ligands and terminal inorganic ligands (OH− and H2O). Specially, the optimized MIL‐100(Fe) catalysts, where there are only terminal inorganic ligand defects and coexistence of dual defects, exhibit the respective 1.7‐ and 7.7‐fold activity enhancement comparable to the pristine catalyst under visible light irradiation. As revealed by experimental and theoretical calculation results, the dual defects in the catalyst induce the formation of abundant and highly accessible coordinatively unsaturated Fe active sites and synergistically optimize their geometric and electronic structures, which favors the injection of more d‐orbital electrons in Fe sites into the N2 π* antibonding orbital to achieve N2 activation and the formation of a key intermediate *NNH in the reaction. This work provides a guidance on the rational design and accurate construction of porous catalysts with precise defective structures for high‐performance activation of catalytic molecules.

Metal organic framework (MOF): Synthesis and fabrication for the application of electrochemical sensing

Metal-organic frameworks (MOF) are a class of porous hybrid materials of metal ions linked by organic bridging ligands. These materials consist of different families of crystalline frameworks with metal ions and metal-ion clusters linked by the coordination bonds with suitable organic ligands. These porous materials possess high surface area, variable pore sizes, various functions, and excellent thermal stability. As a result, these unique and tailored MOF materials found varied applications in electrochemical sensor development. The review critically examines the approach to synthesizing a wide range of MOF compounds. The utilization of MOF in fabricating a small-scale sensor device demonstrates the ability to detect various water contaminants in aquatic environments. Moreover, it showcased an in-depth advancement in sensor and device development utilizing MOFs materials. The efficient use of electrochemical sensors is discussed critically and presents these studies’ challenges and future perspectives.

Tumor-targeted delivery of SNHG15 siRNA using a ZIF-8 nanoplatform: Towards a more effective prostate cancer therapy

Small interfering RNAs (siRNAs) can be used as a powerful tool in gene therapy to downregulate the expression of specific disease related genes. Some properties however, such as instability, and low penetration into cells can limit their efficacy, and thus reduce their therapeutic potential. Metal-organic frameworks (MOFs) such as zeolitic imidazolate framework-8 (ZIF-8), which consist of organic bridging ligands and metal cations (Zn), have a very high binding affinity with nucleic acids including siRNAs. In this study, we designed a PEGylated ZIF-8 platform that was equipped with epithelial cell adhesion molecule (EpCAM) aptamer for the targeted delivery of siRNA molecules, in order to knockdown SNHG15 in both a prostate cancer (PC) cell line, and a human PC xenograft mouse model. SNHG15 is a long noncoding RNA, with oncogenic roles in different cancers including PC. The results indicated that the depletion of SNHG15 by Apt-PEG-siRNA@ZIF-8 nanoplatfrom inhibited cell proliferation and colony formation, and increased apoptosis in PC cells. This nanoparticle facilitated the release of siRNAs into the tumor environment in vivo, and subsequently reduced the tumor growth, with no side effects observed in vital organs. We have therefore developed a novel siRNA nano-delivery system for targeted prostate cancer treatment; however further studies are required before it can be tested in clinical trials.

Syntheses, structures, photoelectricity and photocatalysis of 2-D and 3-D bromoargentate frameworks with organic linkers

Organic bromoargentate hybrids [(mtpy)2(Ag3Br3)]n (1) (mtpy = 2-mercaptopyridine) and [(hmta)(Ag4Br4)]n (2) (hmta = hexamethylenetetramine) were prepared by solvothermal methods in CH3CN and DMF solvents, respectively. In 1, the inorganic (Ag3Br3)n chains were connected by organic μ3-mtpy bridging ligands into a two-dimensional (2-D) [(mtpy)2(Ag3Br3)]n layer containing a 1-D backbone constructed by interconnected adamantane-like Ag4S4Br6 cores. In 2, the inorganic (Ag4Br4)n chains were linked by μ4-hmta bridging linkers to form a 3-D [(hmta)(Ag4Br4)]n framework. Compounds 1 and 2 exhibited sensitive photocurrent responses under Xe light irradiation with steady current densities of 5.85 and 2.01 μA·cm−2, respectively. They were photocatalytically active in the degradation of the organic dyes crystal violet (CV) and methylene blue (MB) in an aqueous solution at room temperature. Compound 1 showed higher catalytic activities for photodegradation of the organic dyes than 2, which was consistent with the stronger photocurrent response of compound 1. The ∙O2− radicals were the main active species, while h+ holes and·OH radicals played synergistic roles in the photocatalytic reaction.

Computational aspects of entropy measures for metal organic frameworks

ABSTRACT A form of porous polymeric material known as metal-organic frameworks is made up of metal ions connected by organic bridging ligands. Entropy is used as a complexity indicator for graphs and is regarded as the graph's structural information content. The graph entropies have evolved into information-theoretic variables for computing the structure information of chemical graphs. The potential use in chemistry of the graph entropy portion has gained the attention of the research community. In this article, we investigate the explicit expressions of graph entropies for two categories of metal organic frameworks (MOFs) named as, M 1 TPyP − M 2 (TPyP= 5, 10, 15, 20-tetrakis (4-pyridyl) porphyrin and M 1 , M 2 = Fe and Co) MOFs and butylated hydroxytoluene-(BHT-) based metal-organic (M= Co, Fe, Mn, Cr) (MBHT) frameworks. we compute some numeric values for certain graph entropies in Tables. In the last, we present a comprehensive graphic comparison of our new results.

Synthesis, Characterization, and Catalytic Performance of Modified Keggin‐type Calix[6]arene‐like Polyoxometalates

AbstractTwo modified Calix[6]arene‐like polyoxometalates of the Keggin type with similar structures were synthesized under hydrothermal conditions by H3PMo12O40. H3PW12O40, 4H‐1,2,4‐triazol‐3‐amine (3‐atrz) and copper ions were used as precursors, respectively, bridging organic ligand and transition metals. The result of single‐crystal X‐ray diffraction and elemental analysis showed that the structural formulas of the two crystalline compounds were: [2(C6H12N12Cu3PW12O40)] (3‐atrz‐Cu‐PW12), and [2(C6H12N12Cu3PMo12O40)] ⋅ 0.5H2O (3‐atrz‐Cu‐PMo12). They were composed of two classic Keggin‐type polyoxometalate anions and six [Cu(C2H4N4)]+ coordination polymers similar to Calix[6]arene. The catalytic studies represented that the two heterogeneous catalysts catalyzed the oxidation of iodide ions in hydrogen peroxide. The catalytic reaction of 3‐atrz‐Cu‐PW12 only took 30 min and 15 s to complete the reaction. The rate of iodine generation was 6.86×10−7 mol L−1 s−1. The 3‐atrz‐Cu‐PMo12 catalytic reaction needed only 1 min and 51 s, in which the rate of iodine generation was 1.126×10−5 mol L−1 s−1. The catalytic reaction rate of 3‐atrz‐Cu‐PMo12 was 16.35 times higher than 3‐atrz‐Cu‐PW12. Both catalysts were reused nine times, and the conversion rate was still 99.96 %, showing excellent catalytic activity and repeatability.

Carbon Based-Materials/Metal-Organic Framework for Catalytic Oxidation in Direct Borohydride Fuel Cell Application

Metal-organic frameworks (MOFs), are known as novel types of crystalline materials formed by organic bridging ligands and coordination of metal ions. MOFs have unique characteristics such as high porosity, large surface area, and high structural durability. However, MOFs have some disadvantages such as having low stability, as well as electrical conductivity which causes their catalysis efficiency and application to be limited to a large extent. Thus, among the solutions made in previous studies, to overcome the disadvantages of this MOF is to combine it with carbon-based material to form a composite with better properties than pure MOF. This current review focuses on the performance of carbon-based material/MOF catalyst composites for direct borohydride fuel cell (DBFC) application. The catalytic oxidation of borohydride performance using carbon-based material/MOF catalyst is clearly and scientifically observed to enhance the catalytic activity in previous studies. There is no denying that carbon-based materials are widely used in fuel cell applications and have great advantages such as low toxicity, unique structure, good porosity properties, lightweight, controllable heteroatom doping, and easy processing, as well as excellent mechanical, chemical, and thermal properties. Thus, this review provides a summary of the application of carbon-based materials and MOFs with the properties and performance of this composite including the catalytic oxidation activity and DBFC potential for the entire system.

Preparation of 2D ZIF-L and Its Antibacterial and Antifouling Properties

The excessively leached metal ions from traditional metallic antimicrobial nanoparticles are harmful to biological and human tissues. Metal-organic frameworks (MOFs) coordinating bioactive metal ions to organic bridging ligands can potentially address this issue, avoiding the excessive leaching of metal ions and simultaneously exhibiting high effective antibacterial activities. Here, we report the preparation of a 2-dimensional leaves-like zeolitic imidazolate framework (ZIF-L) for potential antibacterial and anti-algae applications. The ZIF-L nanosheet exhibits complete inactivation of Escherichia coli (phosphate buffer saline: 4 h) and Bacillus subtilis (seawater: 0.5 h). The ZIF-L/epoxy composite has excellent antibacterial effect, poisoning effect and anti-adhesion effect on a variety of marine algae. It is worth noting that the removal rate (Escherichia coli) for ZIF/epoxy composite can be reached to 90.20% by only adding ZIF-L (0.25 wt%). This work will inspire researchers to develop more metal-organic frameworks materials for applications in the antibacterial and anti-algae fields.

Raman spectroscopy, an ideal tool for studying the physical properties and applications of metal-organic frameworks (MOFs).

Metal-organic frameworks (MOFs) are a unique family of materials constructed by coordinating metal ions or clusters to bridging organic ligands. Many of these materials are well known for their intricate structures, and exceptional gas adsorption properties, and have potential applications in the separation of alkanes, catalysis, energy storage, surface-enhanced Raman spectroscopy (SERS) based detections, and diagnostics. In situ or in operando Raman spectroscopic studies provide real-time information about the different processes and associated structural changes in MOFs. In the last few decades, there has been phenomenal growth in the publications on MOFs containing insights from Raman spectroscopy. Such studies have helped the research community in identifying the adsorption sites, defect sites, structural or spin transitions, reaction centers, intermediates, etc. In this review, we present the current research status of Raman spectroscopy in probing the structure, guest adsorption, catalytic activity, and reaction mechanisms of MOFs, and their application in energy storage and SERS detection. We highlight the advancements in the Raman spectroscopy technique that have facilitated in situ studies in atmosphere as well as various chemical environments. We briefly discuss the relevance of computational studies in understanding phonon modes and predicting the stability of MOFs. Although this review is particularly focussed on works related to Raman spectroscopy of MOFs, we do discuss infrared studies on MOFs, where such results or analyses are missing from the Raman studies. These discussions have been provided with the intent to develop similar analysis techniques or methods in Raman spectroscopy research.

Constructing a Redox-Active Cu(I)-Pyridyltriazine Framework for Catalytic Photoreduction of Nitrobenzenes and Carboxylic Cyclization of Alkynol with CO2.

A redox-active metal-organic framework, Cu(I)-TPT, was synthesized by combination of Cu(I), the halogenoid cyanide group (CN), and redox-active organic bridging ligand 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) into one single framework. Cu(I)-TPT displays a two-dimensional (2D) plane structure by 1D -Cu(I)-CN- chains connected with TPT ligands. Cu(I)-TPT exhibits intrinsic semiconductive features with a moderate bandgap energy (1.97 eV). Under irradiation, Cu(I)-TPT has an electrical conductivity of 2 × 10-7 S cm-1 in the presence of the sacrificial electron donor ethanol under the ambient test conditions, which is owing to the π-π stacking interactions between TPT moieties, the d-π conjugation between the Cu(I) ion and the CN ligands, and the permanent microporosity. Cu(I)-TPT displayed highly efficient hole-electron separation and ordered electron transfer, which is beneficial for the photoreduction of nitrobenzene. In addition, Cu(I)-TPT displays high efficiency in carboxylic cyclization of alkynol with CO2 because it possesses highly decentralized Cu(I) catalytic sites to the active C≡C bond of alkynol and affluent N atoms on the 2D sheets to facilitate the trapping and activation of CO2.

Solvent-dependent formation of 1D coordination polymers based on polynuclear copper(II)-carboxylate fragments and 4-(pyridine-3-yl)methyleneamino-1,2,4-triazole linkers

The solvent used for the synthesis and crystallization was shown to affect the composition and structure of compounds formed in the reaction of copper(II) trimethylacetate with a Schiff base, 4-(pyridin-3-yl)methyleneamino-1,2,4-triazole (L). The reaction of [Cu2(piv)4(Hpiv)2] (Hpiv – trimethylacetic acid) in MeCN was found to give the crystals of 1D coordination polymer {[Cu2(piv)4(L)]·MeCN}n (1), the structure of which contains binuclear {Cu2(piv)4} units linked by the bridging organic ligand L. A similar reaction in MeOH or EtOH gave 1D coordination polymers {[Cu6(OH)2(piv)10(L)2(ROH)2]∙4ROH}n (2: R = Me, 3: R = Et) whose structure is composed of alternating binuclear {Cu2(piv)4} and tetranuclear {Cu4(OH)2(piv)6(L)2(ROH)2} units bound by N-donor ligand L. Storage of the mother liquor obtained after the isolation of the crystals of 3 leads to the crystallization of chained polymer [Cu(piv)2L]n (4). The structures of new complexes 1–4 were determined by single crystal X-ray diffraction. According to magnetochemical measurements for 1 and 3, antiferromagnetic exchange interactions are observed in these compounds between CuII ions (S = ½) in binuclear {Cu2(piv)4} units (J = −190.5 and −215 cm−1, respectively), as well as dominate in tetranuclear {Cu4(OH)2(piv)6(L)2(EtOH)2} units of 3 (J1 = −202 cm−1, J2 = –23 cm−1, J3 = 18 cm−1).

From an antiferromagnetic insulator to a strongly correlated metal in square-lattice MCl2(pyrazine)2 coordination solids

Electronic synergy between metal ions and organic linkers is a key to engineering molecule-based materials with a high electrical conductivity and, ultimately, metallicity. To enhance conductivity in metal-organic solids, chemists aim to bring the electrochemical potentials of the constituent metal ions and bridging organic ligands closer in a quest to obtain metal-d and ligand-π admixed frontier bands. Herein, we demonstrate the critical role of the metal ion in tuning the electronic ground state of such materials. While VCl2(pyrazine)2 is an electrical insulator, TiCl2(pyrazine)2 displays the highest room-temperature electronic conductivity (5.3 S cm–1) for any metal-organic solid involving octahedrally coordinated metal ions. Notably, TiCl2(pyrazine)2 exhibits Pauli paramagnetism consistent with the specific heat, supporting the existence of a Fermi liquid state (i.e., a correlated metal). This result widens perspectives for designing molecule-based systems with strong metal-ligand covalency and electronic correlations.

Characterization and Antibacterial Evaluation of Biodegradable Mannose-Conjugated Fe-MIL-88NH2 Composites Containing Vancomycin against Methicillin-Resistant Staphylococcus aureus Strains.

The emergence of bacterial resistance has increased the economic burden of infectious diseases dramatically during the previous few decades. Multidrug resistance (MDR) is difficult to cure in both Gram-negative and positive bacteria and is often incurable with traditional and broad-range antibiotics. Therefore, developing techniques to increase the antibacterial activity of therapeutic drugs is essential. Metal-organic frameworks (MOFs) are extremely versatile hybrid materials made of metal ions coupled via organic bridging ligands. They have been widely used as an excellent vehicle for drug delivery due to their low toxicity, biodegradability, and structural stability upon loading and functionalization. The present study focused on the synthesis of mannose (MNS)-coated MOFs with enhanced surface contact with S. aureus cells. The MNS coating on the surface of MOFs enhances their adherence to bacteria by binding to lectins present on the bacterial cell, resulting in improved VCM cellular penetration and activity against resistant bacteria. Various techniques, including atomic force microscopy, DLS, TGA, FT-IR, and DSC, were employed to analyze MNS-coated MOFs. They were also evaluated for their efficacy against resistant S. aureus. The results indicated that when VCM was loaded into MNS-coated MOFs, their bactericidal activity rose dramatically, resulting in the greater suppression of resistant S. aureus. AFM investigation of S. aureus strains demonstrated total morphological distortion after treatment with MNS-coated drug-loaded MOFs. The results of this work suggest that MNS-coated MOFs may be effective for reversing bacterial resistance to VCM and open new pathways for improving antibiotic therapy for diseases associated with MDR.

Research on the mechanism and application of rigid and flexible metal-organic frameworks in selective adsorption

Metal-organic frameworks (MOFs) are materials with porousness that metal ions and organic bridging ligands make up the composition to join. They are commonly employed in gas separation applications because of their extraordinarily high sorption capacities and complicated sorption behaviour. This article mainly introduces the mechanism and application of rigid and flexible MOFs used in selectively separating various gases. Rigid MOFs are just standard MOFs with rigid backbones and porous frameworks that are comparably stable and strong. Based on molecular sieving effect, interactions between adsorbates and surfaces, and the cooperative effects of size/shape exclusion and adsorbate-surface interactions, rigid MOFs used in selective adsorption of H2, O2, CH4 were highlighted. For flexible MOFs, the crystalline order of the underlying coordination network is combined with cooperative structural transformability in them. Based on size/shape exclusion, adsorbate-surface interactions and gate-opening or structural rearrangement caused by adsorbate-surface interactions, gate-opening forces that are particular to each gate, flexible MOFs used in selective adsorption of C2H2, CO2 and CH4 were discussed.

Coordinating Polymers Based on Nickel(II) and Cobalt(II) Trimesinates as Promising Adsorbents of Organic Dyes

Metal-organic frameworks (MOFs) are crystalline compounds consisting of metal ions coordinated by bridg-ing organic ligands. Depending on the coordination geometry of the metal and the direction of the bond of donor atoms, as well as on the geometry of the bridging ligand, 1D, 2D, or 3D polymer structures are formed. The characteristic features of metal-organic frameworks are low density, high porosity and crystallinity, and large specific surface. Wide attention is paid to the technological aspects of creating such materials and their integration into various devices. To obtain MOFs, various synthetic approaches have been developed based on precipitation reactions at room temperature and under convective heating, including hydrothermal and solvothermal syntheses. In this work, metal organic framework structures based on nickel and cobalt trimesinates were synthesized by a modified procedure by reacting nickel acetate and cobalt nitrate with trimesic acid in the presence of alkali. The obtained compounds were used to study the adsorption of Congo Red and Methylene blue organic dyes from their aqueous solutions. The degree of adsorption depends on temperature and reaches a value of 97% for Congo Red, while for Methylene blue it is 83%. The mechanisms and characteristic parameters of the adsorption process were analyzed using empirical models of Langmuir, Temkin, and Freundlich isotherms, of which the adsorption process was optimally described by the Freundlich model. The calculated thermodynamic parameters indicate the spontaneity of the process and its insignificant endothermic character.

Bioinspired metal–organic frameworks mediated efficient delivery of siRNA for cancer therapy

Small interfering RNA (siRNA) has emerged as a powerful tool in gene therapy to suppress gene expression. However, the fragile properties of siRNA and the low efficiency with non-specific gene delivery systems compromised the therapeutic effect of siRNA. Metal-organic frameworks (MOFs) are hybrid materials constructed by organic bridging ligands and metal cations with extremely high binding affinity with nuclei acids. But the properties of MOF-based nanoparticles, such as short circulation lifetime or non-specificity, hindered its application for cancer therapy. Herein, we fabricated a cancer cell membrane camouflaged zeolitic imidazolate framework 8 (ZIF-8)-based metal–organic frameworks (CAMEL) nanoparticles for targeted delivery of siRNA to knockdown Plk1 gene in tumors. ZIF-8 had high loading efficiency of siRNA, and the MOF-based nucleic acids complexes could be prepared at an adult dose once conveniently, which was not reported yet. MOF facilitated the release of siRNA from lysosomes. Cell membrane coating achieves targeted delivery of siRNA to tumor tissue and subsequent PLK1 silencing for tumor suppression. Our work developed a novel MOF-based nucleic acid delivery system for precise cancer therapy.

Spin Crossover in a Series of Non-Hofmann-Type Fe(II) Coordination Polymers Based on [Hg(SeCN)3]- or [Hg(SeCN)4]2- Building Blocks.

Self-assembly of [Hg(SeCN)4]2- tetrahedral building blocks, iron(II) ions, and a series of bis-monodentate pyridyl-type bridging ligands has afforded the new heterobimetallic HgII-FeII coordination polymers {Fe[Hg(SeCN)3]2(4,4'-bipy)2}n (1), {Fe[Hg(SeCN)4](tvp)}n (2), {Fe[Hg(SeCN)3]2(4,4'-azpy)2}n (3), {Fe[Hg(SeCN)4](4,4'-azpy)(MeOH)}n (4), {Fe[Hg(SeCN)4](3,3'-bipy)}n (5) and {Fe[Hg(SeCN)4](3,3'-azpy)}n (6) (4,4-bipy = 4,4'-bipyridine, tvp = trans-1,2-bis(4-pyridyl)ethylene, 4,4'-azpy = 4,4'-azobispyridine, 3,3-bipy = 3,3'-bipyridine, 3,3'-azpy = 3,3'-azobispyridine). Single-crystal X-ray analyses show that compounds 1 and 3 display a two-dimensional robust sheet structure made up of infinite linear [(FeL)n]2n+ (L = 4,4'-bipy or 4,4'-azpy) chains linked by in situ formed {[Hg(L)(SeCN)3]2}2- anionic dimeric bridges. Complexes 2 and 4-6 define three-dimensional networks with different topological structures, indicating, in combination with complexes 1 and 3, that the polarity, length, rigidity, and conformation of the bridging organic ligand play important roles in the structural nature of the products reported here. The magnetic properties of complexes 1 and 2 show the occurrence of temperature- and light-induced spin crossover (SCO) properties, while complexes 4-6 are in the high-spin state at all temperatures. The current results provide a new route for the design and synthesis of new SCO functional materials with non-Hofmann-type traditional structures.