Thermal and Photophysical Properties of Highly Quadrupolar Liquid‐Crystalline Derivatives of the [closo‐B12H12]2− Anion. Issue 10 (21st January 2019)

• Record Type: Journal Article
• Authors: Ali, Muhammad O.; Lasseter, John C.; Żurawiński, Remigiusz; Pietrzak, Anna; Pecyna, Jacek; Wojciechowski, Jakub; Friedli, Andrienne C.; Pociecha, Damian; Kaszyński, Piotr
• Is Part Of: Chemistry. Volume 25:Issue 10(2019)
• Page Start: 2616
• Page End: 2630
• Publication Date: 2019-01-21
• Subjects: boron -- cluster compounds -- density functional calculations -- synthetic design -- zwitterions; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201805392
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Two series of 1, 12‐bis‐zwitterionic derivatives of the [ closo ‐B12 H12 ] 2− anion (B ), containing either two 4‐alkoxypyridinium groups (1B[ n ]‐ p ) or one 4‐alkoxypyridinium and one 4‐pentylthianium groups (2B[ n ]‐ p ), were prepared and their structural (XRD, DFT), thermal, and photophysical properties were compared with those of the analogous derivatives of the [ closo ‐B10 H10 ] 2− anion (1A[ n ]‐ p and2A[ n ]‐ p ). Some 1, 7‐derivatives ofB were isolated and investigated. Both series1[ n ] and2[ n ] exhibit nematic and crystalline polymorphism; the 12‐vertex derivatives (B ) have higher transition temperatures than those of the 10‐vertex analogues (A ). All compounds fluoresce with quantum yields higher for1B ( Φ F =0.37 for1B[7]‐ p and Φ F =0.27 for2B[7]‐ p ) than those for the 10‐vertex analogues ( Φ F =0.04 for2A[5]‐ p ). DFT calculations demonstrate an order of magnitude lower first hyperpolarizability, β (−ω, ω, 0), for2B[7]‐ p than that for the 10‐vertex analogue2A[7]‐ p (1.7×10 −30 vs. 18.9×10 −30 esu at ω =0). Abstract : Close ranks ! Two series of 1, 12‐bis‐zwitterionic derivatives of the [ closo ‐B12 H12 ] 2− anion, containing either two 4‐alkoxypyridinium groups or one 4‐alkoxypyridinium and one 4‐pentylthianium groups, were prepared. Substitution of the [ closo ‐B12 H12 ] 2− anion with two onium groups leads to zwitterionic liquid–crystalline fluorescent derivatives with directional photoinduced charge transfer (see figure).