A new honeycomb-shaped electroactive metal-organic framework (MOF) has been constructed from an electron deficient naphthalenediimide (NDI) ligand equipped with two terminal salicylic acid groups. π-Intercalation of electron-rich planar tetrathiafulvalene (TTF) guests between the NDI ligands stacked along the walls lowers the electronic band gap of the material by ca. 1 eV. An improved electron delocalization through the guest-mediated π-donor/acceptor stacks is attributed to the diminished band gap of the doped material, which forecasts an improved electrical conductivity.

To diversify metal−organic framework (MOF) structures beyond traditional Euclidean geometries and to create new chargedelocalization pathways beneficial for electrical conductivity, we constructed a novel double-helical MOF (dhMOF) by introducing a new butterflyshaped electron-rich π-extended tetrathiafulvalene ligand equipped with four benzoate groups (ExTTFTB). The face-to-face oriented convex ExTTFTB ligands connected by Zn 2 (COO) 4 paddlewheel nodes formed ovoid cavities suitable for guest encapsulation, while π−π-interaction between the ExTTFTB ligands of neighboring strands helped create new chargedelocalization pathways in iodine-mediated partially oxidized dhMOF. Iodine vapor diffusion led to oxidation of half of the ExTTFTB ligands in each double-helical strand to ExTTFTB •+ radical cations, which putatively formed intermolecular ExTTFTB/ExTTFTB •+ π-donor/ acceptor charge-transfer chains with the neutral ExTTFTB ligands of an adjacent strand, creating supramolecular wire-like chargedelocalization pathways along the helix seams. In consequence, the electrical conductivity of dhMOF surged from 10 −8 S/m up to 10 −4 S/m range after iodine treatment. Thus, the introduction of the electron-rich ExTTFTB ligand with a distinctly convex πsurface not only afforded a novel double-helical MOF architecture featuring ovoid cavities and unique charge-delocalization pathways but also, more importantly, delivered a new tool and design strategy for future development of electrically conducting stimuli-responsive MOFs.

Owing to their abilities to assemble and organize a large number of redox and photoactive components in highly ordered periodic fashion, crystalline porous metal–organic frameworks (MOFs) have the potential to execute myriad complex functions, including charge transport and light to electrical energy conversion when the required conditions are fulfilled. Herein, we demonstrate an unprecedented spontaneous solvothermal growth of precisely [100]-oriented pillared porphyrin framework-11 (PPF-11) films featuring vertically aligned Zn-tetrakis­(4-carboxyphenyl)­porphyrin (ZnTCPP) walls and horizontally aligned 2,2′-dimethyl-4,4′-bipyridine beams attached to annealed ZnO–fluorine-doped tin oxide (FTO) surfaces and their remarkable photovoltaic performance in liquid-junction solar cells. The [100]-oriented PPF-11/ZnO–FTO photoanodes displayed excellent photovoltaic response (short-circuit current (J SC): 4.65 mA/cm2, open-circuit voltage (V OC): 470 mV, power conversion efficiency: 0.86%) that easily outperformed all control devices as well as previously reported porphyrin and Ru­(bpy)3 2+-based visible light-harvesting MOFs with 10–1000 times greater photocurrent density and 2–375 times higher efficiency. The superior photovoltaic behavior of [100]-oriented PPF-11/ZnO films compared to epitaxially grown MOF thin films on insulating self-assembled monolayers and drop-cast PPF films with different orientations can be attributed to several factors, including better charge separation, transport, and injection capabilities of the former. The noncatenated PPF-11 was able to host electron-deficient C60 guests, filling in nearly half of its cavities and engage them in ZnTCPP/C60 charge-transfer interaction. However, the C60-doped PPF-11/ZnO films displayed much weaker photovoltaic response than undoped [100]-oriented PPF-11/ZnO films presumably due to exclusion of I–/I3 – electrolyte from the C60-occupied cavities and the inability of isolated C60 guests to support long-range charge movement.

Herein, we report the synthesis of a double hydrazone capable of undergoing photochemical E/Z isomerization through the imine double bonds. The bis(hydrazone) 1-E,E can be considered as a "two-arm" system in which the controlled movement of each arm is obtained by photo-modulation, making possible the appearance of two isolable metastable isomeric states 1-E,Z and 1-Z,Z. Such states are characterized by very specific structural, optical, and electrochemical properties. The latter allows the reversible return from either 1-E,Z or 1-Z,Z to the 1-E,E state. Our results are of great importance in the further development of molecular machines and photochemically controlled reactions by introducing for the first time double hydrazones as tunable photochemical switches.

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Thermodynamically favored simultaneous coordination of Pt(II) corners with aza- and carboxylate ligands yields tricomponent coordination complexes with sophisticated structures and functions, which require careful structural characterization to paint accurate depiction...

Transforming permanently porous but electrically insulating metal–organic frameworks (MOFs) into electrically conducting materials is key to expanding their utility beyond traditional guest storage, separation, and delivery applications into the realms of modern electronics and energy technologies. To this end, herein, we have converted a highly porous but intrinsically insulating NU-1000 MOF into semiconducting NU-1000/gold nanoparticle (AuNP) and NU-1000/polydopamine/AuNP composites via MOF- and polymer-induced reduction of infiltrated Au3+ ions into metallic AuNPs. The NU-1000/AuNP and NU-1000/PDA/AuNP composites not only gained significant room temperature electrical conductivity (∼10–7 S/cm), which was ca. 104 times greater than any MOF/metal nanoparticle (MNP) composites exhibited thus far under the same conditions, i.e., without photoinduction and thermal induction, but also retained sizable porosity and surface areas (1527 and 715 m2/g, respectively), which were also larger than most intrinsically conducting 3D MOFs developed to date. The markedly higher conductivities of the NU-1000/AuNP and NU-1000/PDA/AuNP composites can be attributed to more efficient charge hopping or tunneling through well-dispersed AuNPs embedded inside the crystalline MOF matrix, which pristine NU-1000 lacked. Thus, this work presented an effective new strategy to transform porous but nonconducting MOFs into electrically conducting MOF/MNP composites with considerable porosity, which could be useful in future electronics, electrocatalysis, and energy storage devices.

A new electrically conducting 3D metal-organic framework (MOF) with a unique architecture was synthesized using 1,2,4,5-tetrakis-(4-carboxyphenyl)benzene (TCPB) a redox-active cis-dipyridyl-tetrathiafulvalene (Z-DPTTF) ligand. While TCPB formed Zn2(COO)4 secondary building units (SBUs), instead of connecting the Zn2-paddlewheel SBUs located in different planes and forming a traditional pillared paddlewheel MOF, the U-shaped Z-DPTTF ligands bridged the neighboring SBUs formed by the same TCPB ligand like a sine-curve along the b axis that created a new sine-MOF architecture. The pristine sine-MOF displayed an intrinsic electrical conductivity of 1 × 10−8 S/m, which surged to 5 × 10−7 S/m after I2 doping due to partial oxidation of electron rich Z-DPTTF ligands that raised the charge-carrier concentration inside the framework. However, the conductivities of the pristine and I2-treated sine-MOFs were modest possibly because of large spatial distances between the ligands that prevented π-donor/acceptor charge-transfer interactions needed for effective through-space charge movement in 3D MOFs that lack through coordination-bond charge transport pathways.