Solid-State Photoconversion of a Discrete Mixed Iodine(I) System to a 1D Polymer.

Area of Science:

• Inorganic Chemistry
• Materials Science
• Crystallography

Background:

• Halogen(I) complexes are valuable synthetic intermediates.
• Previous research has explored various halogen(I) structures, but mixed systems with multiple iodine(I) environments are less understood.
• The development of photoresponsive halogen(I) compounds is an active area of research.

Purpose of the Study:

• To synthesize and characterize the first mixed halogen(I) complex containing three distinct iodine(I) moieties.
• To investigate the photochemical behavior of this novel complex under UV irradiation.
• To explore the potential for nondestructive photoconversion of halogen(I) complexes.

Main Methods:

• Synthesis of novel iodine(I) complexes using 4-styrylpyridine and 3,4,5,6-tetrafluorophthalate.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy (¹H, ¹H-¹⁵N HMBC).
• Single-crystal X-ray diffraction (SCXRD) and vibrational spectroscopy (Raman, IR).

Main Results:

• The first mixed halogen(I) complex (2) with [N-I-N]⁺, O-I-N, and [O-I-O]⁻ moieties was successfully synthesized.
• Complex 2 was found to be in equilibrium with its bis(OIN) analogue (1a) and could convert to 1a in solution.
• UV irradiation induced a single-crystal-to-single-crystal [2+2] cycloaddition, converting complex 2 into a 1D polymer (5) without loss of iodine(I) units.

Conclusions:

• A novel mixed halogen(I) complex with unprecedented structural diversity was created.
• The complex exhibits interesting photochemical reactivity, undergoing nondestructive [2+2] cycloaddition upon UV exposure.
• This work presents the first example of nondestructive photoconversion in a halogen(I) complex, opening new avenues for photoresponsive materials.