It is known from several examples reported in the literature that hydration-dehydration of MOFs can significantly change the 3D-structure of the metal-organic framework. For MIL-53, an aluminum terephthalate, a breathing effect was observed upon hydration-dehydration with a compressed Ganetespib HSP (e.g. HSP90) inhibitor structure for the dehydrated MOF [6]. A similar observation was made for the nanoporous coordination polymer [Ag6Cl(atz)4] (atz = 3-amino-1,2,4-triazolate) [7]. Here, hydration-dehydration induces a remarkable crystal interconversion between two different tetragonal structures. Adsorption of ethanol from the vapor phase was investigated using a Ni-based MOF [8]. Interestingly, only slight structural Inhibitors,Modulators,Libraries readjustment upon sorption and desorption of the simple alcohol was found.

Humidity is of great importance in a wide field of domestic and industrial applications, e.g. the quality control of production processes Inhibitors,Modulators,Libraries or an intelligent control of the living conditions in buildings [9]. From this multiple applications, different requirements arise for humidity sensors, e.g., operating temperature, humidity range, solvent stability [10]. To meet these requirements, a wide variety of sensor mechanisms was investigated for the detection, e.g., optical, resistive, capacitive, piezoresistive, gravimetric, or magnetoelastic [11]. The materials used for these sensors Inhibitors,Modulators,Libraries mainly originate from the ceramic, polymer, and semiconducting materials class [12], whereas metal-organic framework materials have not yet been investigated for this purpose to our knowledge.

The sensing mechanism of the different materials is mainly based on physical adsorption or absorption of water molecules from the surrounding atmosphere causing a change in the electrical properties Inhibitors,Modulators,Libraries (impedance or resistance and capacitance) of the sensing material [13].Each of these sensor types suffers from limitations, so intensive research in this field continues. The main drawback of these sensors is that they are mostly only designed to detect relative humidity (rH) in the range of 10 �C 90 % rH and to work at room temperature or slightly above [14]. Ceramic humidity sensors have to deal with the formation of stable chemisorbed OH? at their surface. To avoid a drift in the resistance of those ceramic sensors induced by chemisorption, a periodic heat treatment at temperatures higher than 400 ��C is necessary to regenerate the sensor surface [15].

Hence, ceramic Brefeldin_A humidity selleck sensors are often equipped with a supplementary heater for this regeneration process causing extra cost and complexity [16]. This heat cleaning is not necessary for polymer sensors and their fabrication cost is much lower than for ceramic ones, as they do not need high-temperature processing [17]. However, polymers often lack thermal or chemical stability and cannot be used as humidity sensors in harsh environments. Moreover, polymer film sensors show slow response times, hysteresis and long-term drift when exposed to some solvents [10].