Photoressive cages are promising for accordable supramolecular electronics

In a recent study that merges supramolecular chemistry and molecular electronics, a research team has shown how supramolecular porphyrin cages can allow loading behavior (CT) on photoreplication granted in semiconductor devices. The results could open the way to more versatile and controllable molecular components in optoelectronic applications.

Research is published in the journal International edition of Angewandte Chemie.

The collaborative team was led by Professor Cunlan Guo of Wuhan University, Professor Ming Wang of Jilin University and Professor Haohao FU of Nankai University.

Molecular electronics have long been based on the structural versatility of small molecules to adjust load transport behavior. But as demand increases for devices of devices with dynamic responsiveness, supramolecular assemblies draw attention to their ability to refine the flow of electrons via weak and reversible interactions and external stimuli. Among various stimuli, light is distinguished by its spatial precision and non -invasion – qualities ideally adapted to new generation functional devices such as molecular switches.

To meet the need for molecular architectures sensitive to light with robust and predictable properties, the team turned to porphyrins – aromatic planar and macrocycles known for their photoscability and strong absorption in the visible beach. By coordinating porphyry derivatives with a Bidentinum (II) motif (II), they built well-defined supramolecular structures (C-TPYP) with rigid pillars and a separation distance from ~ 18,3 Å between porphyrine faces.

The electrical junctions built from these supramolecular cages, sandwiched between a self-assembly monolayer (SAM) and an Egain upper electrode, presented distinctly different behaviors under the light. While the junctions containing monomeric porphyrins have shown negligible changes of 420 Nm lighting, those made with supramolecular cages showed marked photorepatic load transport. In particular, the inclusion of metallic ions such as ZN²⁺ and Cu²⁺ in porphyrin cores has changed the extent of this response, highlighting the taxation of the system.

In support of these electrical measurements, fluorescence spectroscopy and microscopy by Kelvin’s (KPFM) probe confirmed that supramolecular architecture has improved the separation of electron holes – an effect directly correlated with the behavior of the observed photoring current.

Other experiments have shown that the distance between porphyrin cages and the gold substrate – has modified by varying the length of the alcanethiol spaceman in SAM – affected CT efficiency. While increased distances have attenuated the response induced by light, the too short spacers have removed molecular behavior, probably due to excessive coupling to the electrode.

This study not only advances the fundamental understanding of transportation of charges in supramolecular systems, but also offers a practical framework for optorelectronic devices on the molecular engineering scale. Work underlines how molecular design, assembly accuracy and interfacial engineering can converge to create electronic elements that are functional sensitive to environmental signals.