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High‐quality MOF thin films with high orientation and controlled thickness are extremely desired for applications. However, they have been only successfully fabricated on flat substrates. Those MOF 2D thin films are limited by low exposed area and slow mass transport. To overcome these issues, MOF 3D thin films with good crystallinity, preferred orientation, and precisely controllable thickness in nanoscale were successfully prepared in a controllable layer‐by‐layer manner on nanowire array substrate for the first time. The as‐prepared Cu‐HHTP 3D thin film is superior to corresponding 2D thin films and showed one of the highest sensitivity, lowest LOD, and fastest response among all reported chemiresistive NH3 sensing materials at RT. This work provides a feasible approach to grow preferred‐oriented 3D MOF thin film, offering new perspectives for constructing MOF‐based heterostructures for advanced applications. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid superlattices (OIHSLs) hold attractive physical and chemical properties, while the construction of single‐crystal covalent OIHSLs has not been achieved. Herein a coordination assembly strategy was proposed to create a single‐crystal covalent OIHSL PbBDT (BDT=1,4‐benzenedithiolate), where layered [PbS2] sublattice covalently connects with benzene sublattice. The covalent bonding offers better thermo‐/chemi‐stability, inter‐sublattice electron transport, and unique organic‐group‐functionalized surface, which may enable better performances in chemical applications than non‐covalent OIHSL. These features endow PbBDT with the highest sensitivity, the lowest detection limit and excellent selectivity towards NO2 at room temperature among all chemiresistive gas‐sensing materials with reported response time less than 2 min without the need of light assistance. [ABSTRACT FROM AUTHOR]

In this paper, a dual-ligand design strategy is demonstrated to modulate the performance of the electronically conductive metalorganic frameworks (EC-MOFs) thin film with a spray layer-by-layer assembly method. The thin film not only can be precisely prepared in nanometer scale (20–70 nm), but also shows the pin-hole-free smooth surface. The high quality nano-film of 2,3,6,7,10,11-hexaiminotriphenylene (HITP) doped Cu-HHTP enables the precise modulation of the chemiresistive sensitivity and selectivity. Selectivity improvement over 220% were realized for benzene vs. NH3, as well as enhanced response and recovery properties. In addition, the selectivity of the EC-MOF thin film sensors toward other gases (e.g. triethylamine, methane, ethylbenzene, hydrogen, butanone, and acetone) vs. NH3 at room temperature is also discussed. [ABSTRACT FROM AUTHOR]

Heterostructured metal—organic framework (MOF)‐on‐MOF thin films have the potential to cascade the various properties of different MOF layers in a sequence to produce functions that cannot be achieved by single MOF layers. An integration method that relies on van der Waals interactions, and which overcomes the lattice‐matching limits of reported methods, has been developed. The method deposits molecular sieving Cu‐TCPP (TCPP=5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin) layers onto semiconductive Cu‐HHTP (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene) layers to obtain highly oriented MOF‐on‐MOF thin films. For the first time, the properties in different MOF layers were cascaded in sequence to synergistically produce an enhanced device function. Cu‐TCPP‐on‐Cu‐HHTP demonstrated excellent selectivity and the highest response to benzene of the reported recoverable chemiresistive sensing materials that are active at room temperature. This method allows integration of MOFs with cascading properties into advanced functional materials. [ABSTRACT FROM AUTHOR]