The Supramolecular Structures and Photo-Physical Properties Modulated by Spacer Lengths in 1,ω-Bis(isoquinoline)Alkane/(Bi₄I₁₆)⁴⁻ Hybrids

The study about the supramolecular interactions in the organic–inorganic hybrids will be significant for the design of new photo/electrical functional materials. In this work, 1,ω-bis(isoquinoline)alkane cations with different spacer lengths (n = 3, 5, 6) have been incorporated with iodobismuthates to construct three new hybrids, which have been formula as [BIQPP]₂[Bi₄I₁₆] (1), [BIQPT]₂[Bi₄I₁₆] (2) and [BIQHX]₂[Bi₄I₁₆] (3) through X-ray single crystal diffraction method (BIQPP²⁺ = 1,3-bis(isoquinoline)propane, BIQPT²⁺ = 1,5-bis(isoquinoline) pentane, BIQHX²⁺ = 1,6-bis(isoquinoline)hexane). The centrosymmetric [Bi₄I₁₆]⁴⁻ anions are constructed from four edge-sharing BiI₆ octahedra. Interestingly, with the elongation of spacer length on isoquinoline from 3, 5 to 6, the iodobismuthate anions exhibit 0-D [Bi₄I₁₆]⁴⁻ tetramers (n = 3, 6 for 1 and 3) and pseudo 3-D [Bi₄I₁₆]_n⁴ⁿ⁻ network (n = 5, for 2) based on I···I interactions. Supramolecular interactions including π–π stacking interactions and C–H···I hydrogen bonds contribute to their structural extensions. Consequently, the enhanced red emission intensity and the lower thermochromic temperature can be observed in 2. The clarification on the spacer effect on the supramolecular interactions and functional properties of this work will be beneficial for the design of new functional materials.

Different iodobismuthate anions and photo-physical properties including red emission intensity and thermochromism can be achieved by elongating the spacer lengths in 1,ω-Bis(isoquinoline)alkane cations