866220-44-2Relevant academic research and scientific papers
Effect of the Molecular Conformation on Excitation Energy Transfer in Conformationally Constrained Boryl-BODIPY Dyads
Nandi, Rajendra Prasad,Chinna Ayya Swamy,Dhanalakshmi, Pandi,Behera, Santosh Kumar,Thilagar, Pakkirisamy
supporting information, p. 5452 - 5462 (2021/05/06)
We studied the dual emission characteristics of a series of boryl-BODIPYs (1-6) comprised of triarylborane (TAB) as an energy donor and BODIPY as an energy acceptor. The molecular conformations of dyads 1-6 were systematically tuned by judiciously changing the spacer that bridged the boryl and BODIPY moieties. Frontier molecular orbitals (FMOs) are localized in 3, 4, and 6 with a twisted molecular conformation. In contrast, FMOs are significantly delocalized in 1, 2, and 5 with the least-twisted molecular conformation. Dyads 1-6 showed dual emission features when they were excited at the TAB-dominated absorption band. However, the ratio between the two emission bands in 1-6 significantly varied depending on the molecular conformations. Systematic photoluminescence (PL) studies (both steady-state and time-resolved PL) together with computational, crystal structure, and anion binding studies established that the frustrated excited-state energy transfer from borane to BODIPY is the cause of the dual emission features in these molecular dyads. These studies also revealed that the energy transfer from borane to BODIPY can be elegantly tuned by modulating the dihedral angle between these two moieties.
Intriguing ‘Turn-on’ phosphorescent response in the near infrared region upon fluoride binding: Dipyrromethene chelating-based Triarylboryl?Iridium(III) conjugates
Hong, Ju Hyun,Hwang, Hyonseok,Kim, Seonah,Lee, Ji Hye,Lee, Kang Mun,So, Hyunhee
, (2020/08/21)
Two novel heteroleptic cyclometalated iridium(III) complexes, namely (C^N)2Ir(BL) (Ir1 and Ir2) (C^N = 2-(2,4-difluorophenyl)pyridine (dfphpy, for Ir1) and 2-phenylpyridine (phpy, for Ir2)), chelated by the triarylboryl dipyrromethene ancillary ligand (BL) were synthesized and characterized. The molecular structures of both complexes in the solid state were fully analyzed by single-crystal X-ray diffraction, and were found to be composed of Ir(III)-centered triarylborane conjugated systems. The UV–vis absorption spectra of both complexes displayed the typical 1MLCT (metal-to-ligand charge transfer) absorption bands centered at λabs = 483 nm, in addition to borane-centered CT absorption bands at ~326 nm. The photoluminescence (PL) spectra for these complexes demonstrated phosphorescent emission in the near infrared region (λem = ~690 nm), which was mainly attributed to the 3MLCT transition (L = BL). In addition, fluoride titration experiments using these complexes showed gradually quenched absorption bands in the region of 300–350 nm, corresponding to borane-centered CT transitions. Furthermore, 1H NMR experiments in THF-d8 for both complexes in the presence of fluoride sources revealed that the fluoride was bound to the dimesitylboryl moieties. Interestingly, upon the addition of fluoride, the PL spectra exhibited a ratiometrically ‘turn-on’ and gradually blue-shifted emissive response. Computational calculations and cyclic voltammetry measurements using the neutral Ir(III)-conjugates and their fluoride adducts strongly suggested that the intriguing emissive response is the result of fluoride binding interrupting the original 3MLCT transition, reinforcing the dipyrromethene-centered π–π* transition, and further inducing the enhancement of the band-gap.
Triarylborane conjugated acacH ligands and their BF2 complexes: Facile synthesis and intriguing optical properties
Kumar, George Rajendra,Thilagar, Pakkirisamy
, p. 3871 - 3879 (2014/03/21)
A facile synthetic route for a new class of organoborane compounds (Mes)2B-arene-acacH and (Mes)2B-arene-acacBF2 (Mes = mesityl and arene = C6H4 or C6Me 4) is reported. The new dyads exhibit intriguing photophysical properties. A small structural change in spacer connecting the two chromophores leads to fine tuning of photophysical properties. The dyad containing 2,3,5,6-tetramethyl phenyl spacer acts as a selective turn-on chemodosimetric sensor for cyanide ion. Steric crowding around the boron centre significantly alters anion binding events. From NMR titration studies it is established that fluoride and cyanide follow different binding mechanisms which lead to intriguing optical properties in the reported probes.
Triarylborane-dipyrromethane conjugates bearing dual receptor sites: The synthesis and evaluation of the anion binding site preference
Swamy P., Chinna Ayya,Priyanka, Ragam N.,Thilagar, Pakkirisamy
, p. 4067 - 4075 (2014/03/21)
The synthesis and optical properties of four new triarylborane- dipyrromethane (TAB-DPM) conjugates (3a-d) containing dual binding sites (hydrogen bond donor and Lewis acid) have been reported. The new compounds exhibit a selective fluorogenic response towards the F- ion. The NMR titrations show that the anions bind to the TAB-DPM conjugates via the Lewis acidic triarylborane centre in preference to the hydrogen bond donor (dipyrromethane) units.
Dual emissive borane-BODIPY dyads: Molecular conformation control over electronic properties and fluorescence response towards fluoride ions
Swamy P, Chinna Ayya,Mukherjee, Sanjoy,Thilagar, Pakkirisamy
supporting information, p. 993 - 995 (2013/02/23)
Facile synthesis of two new dimesitylboryl appended BODIPYs is reported. The two dyads have similar fluorescent chromophores but differ in their molecular conformations. They exhibit dual fluorescence, intramolecular energy transfer between boryl and BODIPY chromophores and different fluorescence responses (emission enhancement and quenching) upon fluoride binding. The Royal Society of Chemistry 2013.
