# Synthesis and structural characterization of the Z-isomer of 1,2-bis(tetrazol-5-yl)ethylene (H2bte) via photoinduced isomerization

## TL;DR

Researchers successfully synthesized and characterized the Z-isomer of a compound using UV light, revealing structural differences and potential applications in energetic materials.

## Contribution

The first successful synthesis and structural characterization of the Z-isomer of H2bte via photoinduced isomerization.

## Key findings

- Z-H2bte crystals exhibit a non-planar structure and distinct hydrogen-bonding network compared to the E-isomer.
- Sodium and cesium complexes of both isomers show similar packing and coordination modes.
- Photoinduced isomerization offers a pathway to modulate molecular properties in energetic systems.

## Abstract

This study demonstrates the photoinduced E→Z isomerization of 1,2-bis(tetrazol-5-yl)ethylene (H2bte), leading to the first successful growth and structural characterization of its Z-isomer single crystal. Through optimized 365 nm UV irradiation and subsequent recrystallization, phase-pure Z-1,2-bis(tetrazol-5-yl)ethylene (Z-H2bte) (91.9%) was obtained. Single-crystal X-ray diffraction analysis uncovered a non-planar molecular structure for Z-H2bte, which fosters a distinct hydrogen-bonding network and crystal packing architecture compared to the planar E-isomer. The two isomers were further applied to the construction of sodium and cesium-based metal complexes, with the findings indicating that both isomers present a similar packing and connection mode. This work establishes an experimental foundation for understanding the E/Z photoisomerization and concomitant structural evolution in the H2bte system, while providing a potential pathway for modulating energetic molecular properties through photoinduced cis–trans isomerization.

Z-1,2-Bis(tetrazol-5-yl)ethylene was synthesized, crystals were obtained and the photochemical and physicochemical properties revealed. Sodium and cesium complexes of the E/Z-isomer were constructed and their coordination modes were elucidated.