Hybrid Material for Detecting Vapors of Acids and Bases

The main advantages are based on the type of sensor and the material fabricated for this sensor: There exist different methods and technologies for detecting volatile chemical compounds (gas chromatography – mass spectroscopy, solid phase microextraction, quantum cascade lasers, semiconducting metal oxide chemoresistive sensors, high-performance liquid chromatography, photo ionization detectors or amperometric sensors), however they are expensive, time-consuming, non-portable, require of an expert user, and/or exhibit low selectivity and poor sensitivity. In contrast, luminescence-based sensors are among the most promising as they fulfill most of desired characteristics for a sensor: (i) high sensitivity and selectivity; (ii) they can be portable; (iii) low manufacturing cost; (iv) fast response, and (v) ease of use. In this sense, for fabricating a suitable luminescence sensor, it is critical to develop novel luminescent materials that can efficiently detect the presence of volatile compounds by changing their emission properties. Luminescent metal-organic frameworks (LMOFs) have arisen as one of the most important candidates for developing luminescent sensors. Although a considerable number of LMOFs have been used for chemical detection, most examples are based on detecting substances in solutions. However, the detection of chemical compounds in the vapor phase is less common. Our developed material has demonstrated to efficiently detect toxic chemicals in vapor phase (acids and bases). To this end, we have encapsulated different proton transfer dyes within the pores of various MOFs to detect those analytes, a radical novel concept not explored hitherto. The advantages of our material over other type o luminescent compounds are: i) the encapsulation of the proton transfer dyes within MOFs yields materials with a high robustness (long stability). ii) The proton transfer dyes usually show a large stokes-shift preventing for undesired phenomenon such as autoabsorption. iii) Our material is able to detect both, acids and base vapors by changing its emission color, something that can be followed even by the naked eye. iv) Our material can be fabricated in large scale by a simple, fast, and cost-effective method.