I. Gas adsorption properties and porosity of transition metal-based cyanogels. II. Novel energy transfer processes in organic light-emitting devices.

摘要

The gas adsorption properties and porosity of cyanide-bridged transition metal-based gels are investigated in the first part of this dissertation. The cyanide bridges, connecting two transition metal centers, are characteristic of these gels; hence, these gels are termed cyanogels. Aerogel versus xerogel structures have a profound effect, both, on the thermodynamics and kinetics of gas adsorption on these cyanogels. Carbon dioxide is selectively adsorbed on palladium-cobalt-based cyanogels; the adsorption is fully reversible on both types of gels discussed. The thermodynamics and kinetics of the gas adsorption processes on these gels are analyzed here. From the ease and reproducibility of the CO₂ desorption and the associated enthalpy values, it is concluded that CO₂ is physisorbed on these gels. Both the adsorption and desorption processes are first-order in the gels. Adsorption of carbon monoxide on the palladium-cobalt cyanogels is also investigated. Unlike CO ₂ physisorption, carbon monoxide is chemisorbed on these gels. An uptake of CO brings about a profound change in the xerogel morphology.; The palladium-cobalt-based aerogels possess both micro- and mesoporosity; the xerogels are predominantly microporous with a narrow microporosity. The aerogel surfaces are found to be fractal as analyzed by gas adsorption. Unlike the aerogels, the xerogels do not possess surface fractality. The mechanism of adsorption of different gases on these gels is analyzed based on the gel morphologies.; These transition metal-based gels are promising for a variety of applications such as heterogeneous catalysts, gas filters and magnetic materials. The porosity of these gels can be exploited to make gel-embedded filters to separate mixtures of gases based on the their differential adsorption propensities. The reversible adsorption of CO₂ can be harnessed practically by using these gels as CO₂ storage reservoirs.; In the second part of this dissertation, the first, balanced, white-emitting organic light-emitting device (OLED) is demonstrated. This OLED is based on a novel mechanism of energy transfer termed interlayer sequential energy transfer. The relative red-, green-, and blue-emission intensities in this OLED can be independently tuned by the means of two separate parameters.