Energy transport in dichromic metallo-organic crystals: selective inclusion of spatially-resolved arrays of donor and acceptor dyes in different nanochannels

In this study, the precise positioning and alignment of arrays of two different guest molecules in a crystalline host matrix has been engineered resulting in new optically-active materials. Sub-nm differences in the diameters of two types of 1D channels is sufficient for size-selective inclusion of dyes. Energy transport occurs between the arrays of different dyes that are included in parallel-positioned nanochannels by fluorescence resonance energy transfer (FRET). Dichromism and diattenuation of individual micro-sized crystals are dependent on their relative position under polarized light. This angular-dependent behavior is a result of the geometrically-constrained orientation of the dyes by the crystallographic packing of the host matrix and is concentration dependent. These functionalized crystals can find applications in optical switches and as bulk materials for light harvesting and up-conversion.