Near-infrared-emissive π-conjugated polymers based on five-coordinated silicon formazanate complexes

• Published in: Polymer (Guilford) Vol. 239; p. 124463
• Main Authors: Ito, Shunichiro, Ito, Yoshinori, Kazuo, Tanaka, Chujo, Yoshiki
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 17.01.2022; Elsevier BV
• Subjects: Conjugation; Energy gap; Functional materials; I.R. radiation; Infrared radiation; Ligands; Mathematical analysis; Near-infrared emission; Organic compounds; Polymers; Silicon; Silicon complex; Silicon compounds; π-Conjugated polymer; π-Conjugated polymer; Silicon complex; Near-infrared emission
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2021.124463

Organic compounds interacting with near-infrared (NIR) light are vital for developing next-generation functional materials. Herein, silicon formazanate complexes and their conjugated polymers with near-infrared luminescence were synthesized using the N2O2-type formazanate ligands. In the calculated geometries, the silicon atom possessed square-pyramidal structures. Interestingly, the photophysical properties of the complexes were strongly affected by the types of axial ligands. π-Conjugation efficiently extended through the polymer chains, resulting in narrow energy gaps between frontier orbitals. The emission band from spin-coat films reached the NIR II region (>1000 nm). Theoretical calculations revealed that the square-pyramidal structure at the coordination center should be responsible for the efficient π-conjugation. [Display omitted] •Near-infrared emission was obtained from five-coordinated silicon formazanates and their polymers.•Quantum calculations suggested that the axial ligands regulate the HOMO levels.•Polymeric structure improved the stability of the chromophores.