Novel Molecular Building Blocks Based on the Boradiazaindacene Chromophore: Applications in Fluorescent Metallosupramolecular Coordination Polymers

Abstract

Bright polymers: Fluorescent coordination polymers made up of versatile functionalized bodipy (boron‐dipyrrin) chromophore building blocks, such as that depicted, are described. Polymerization is signaled by changes in fluorescence emission intensity and shifts in peak emission wavelengths.magnified imageWe designed and synthesized novel boradiazaindacene (Bodipy) derivatives that are appropriately functionalized for metal‐ion‐mediated supramolecular polymerization. Thus, ligands for 2‐terpyridyl‐, 2,6‐terpyridyl‐, and bipyridyl‐functionalized Bodipy dyes were synthesized through Sonogashira couplings. These fluorescent building blocks are responsive to metal ions in a stoichiometry‐dependent manner. Octahedral coordinating metal ions such as ZnII result in polymerization at a stoichiometry corresponding to two terpyridyl ligands to one ZnII ion. However, at increased metal ion concentrations, the dynamic equilibria are re‐established in such a way that the monomeric metal complex dominates. The position of equilibria can easily be monitored by 1H NMR and fluorescence spectroscopies. As expected, although open‐shell FeII ions form similar complex structures, these cations quench the fluorescence emission of all four functionalized Bodipy ligands.

Deep‐red emissive conjugated poly(2,6‐BODIPY‐ethynylene)s bearing alkyl side chains

“…The solubility of BODIPY‐based conjugated polymers can be controlled by functionalization of meso‐phenyl ring with a large variety of substituents at different positions. Very recently, BODIPY‐based conjugated copolymers and co‐oligomers have been reported 29, 30. In this article, we demonstrate the feasibility of the hypothesis to prepare new kind of deep‐red emissive conjugated polymers with triple‐bond connections between BODIPY cores at positions 2 and 6, poly(2,6‐BODIPY‐ethynylene)s bearing dodecyl side chains (Polymers A , B and C ) (Scheme ).…”

Functional Supramolecular Architectures of Dipyrrin Complexes

“…A 1D coordination polymer containing fluorescent BODIPY units exhibited a unique dynamic equilibrium between the polymeric and monomeric state. The β positions of BODIPY was modified with (ethynylphenyl)terpyridyl groups so that the octahedral coordination of the terpyridyl ligands with Zn(II) ions produced a one-dimensional polymer 15 (Figure 9A ) (Bozdemir et al, 2009 ). Upon the addition of the Zn(II) ion, 1 H NMR signals of the ligand were broadened, indicating the formation of the coordination polymer.…”

Functionalized boron-dipyrromethenes and their applications

“…66 The compounds, 2-tetraphenylethene BODIPY 53, 2-ethynylterpyridyl BODIPY 54, and 2-ethynylbipyridyl BODIPY 55 were also synthesized ( Figure 10A) under Pd(0) conditions by the reaction of 2-halo BODIPY with boronic acid/ethynyl compound. 62,67,68 Using the 2-formyl BODIPY 48, a few BODIPY derivatives were synthesized under Schiff base and Knoevenagel reaction conditions and these derivatives were used for sensing various metal ions. For example, compound oxime BODIPY 56 was Figure 10B) and used to sense OClion whereas compound 57 was used for detection of Hg 2+ ion.…”

“…The 2,6dihalogenated BODIPYs 75-77 were prepared by treating appropriate BODIPY with NXS or X 2 (Br 2 , Cl 2 , I 2 ) in CH 2 Cl 2 ( Figure 13A) at room temperature or other slightly varied reaction conditions. 61,62 Recently Wang et al showed that the regioselective dihalogenation at 2,6-positions of BODIPY 2 can be much faster when reactions were carried out in hexafluoro-2-propanol ( Figure 13A) using NXS as the halogen source. 78 The 2,6-diformyl BODIPY 78 was prepared by treating 2-formyl BODIPY 48 under Vilsmeier-Haack reaction conditions ( Figure 13B).…”

“…The 2,6-bis(ethynylterpyridyl) BODIPY 85 was prepared ( Figure 14B) by the reaction of 2,6-dihalo BODIPY 77 with ethynylterpyridyl under Sonogashira coupling conditions. 62 The formyl groups present at 2,6-pyrrole carbons of BODIPY 78 were used mainly for Schiff base and Knoevenagel condensation reactions and produced new functionalized BODIPYs 86-92 as shown in Figure 14C. The 2,6-dihydroxyl BODIPY 92 was prepared by reducing the formyl groups two steps; the 2,6-dicarboxylic acid substituted BODIPY 91 was prepared by oxidation of formyl groups of 2,6-diformyl BODIPY 78 with NaClO 2 ; the hydroxypropyl substituted BODIPY 88 was synthesized by treating 2,6-diformyl BODIPY 78 with ethylmagnesium bromide; and the dialkenylnitro substituted BODIPY 90, divinylcyanoacetic acid substituted BODIPY 87 were synthesized under Knoevenagel conditions by treating the 2,6-diformyl BODIPY 78 with nitromethane/cyanoacetic acid.…”