Quantum yield and morphology control of BODIPY-based supramolecular self-assembly with a chiral polymer inhibitor

Abstract

Chiral rod-coil-type organoboron polymers S-poly and R-poly were prepared from the palladium-catalyzed SonogashiraHagihara coupling reaction of boron dipyrromethene-based monomer 1, which has bisiodophenyl and decyl groups with S-or R-6,6¢-diethynyl-2,2¢-dioctyloxy-1,1¢-binaphthyls (S-2 and R-2), in a solvent mixture (tetrahydrofuran (THF)/triethylamine¼2/1 (v/v)) at 40 1C for 24 h. The obtained polymers were characterized by hydrogen-1 nuclear magnetic resonance (NMR), carbon-13 NMR ( 13 C NMR), boron-11 NMR ( 11 B NMR) and infrared spectroscopy. The scanning electron microscopy (SEM) analysis of each chiral polymer clearly revealed micrometer-sized fiber-like structures formed by the aggregation of each particle, as we expected. Next, we examined the relationship between the ratio of photoluminescence (PL) intensity (I/I 0 ¼R-poly/S-poly) and particle diameter, measured by dynamic light scattering analysis, versus the R-poly content of the mixed polymer of S-poly and R-poly in THF, which varied from 0 to 100%. As a result, the PL intensity and diameter showed maximum and minimum (about 32 nm) values, respectively, at 70% content, depending on the differences between both the molecular weights and absolute values of the chiral characters. These findings indicate that the PL intensity of S-poly influences morphology change by adding R-poly; that is, R-poly acts as an inhibitor toward the aggregation of S-poly. Furthermore, the SEM image of the mixed polymer (S-poly/R-poly¼30/70) showed complete particle structures from nano-to micrometer sizes, which were roughly 480 nm to 1.19 lm in diameter, and the U F of the mixed polymer was significantly high (0.98).

4,4′-Difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) as components of novel light active materials

“…53). 129 The absorption and emission of each diastereomer were found to be identical, as well as to those of the monomer. Both the R-and Spolymers displayed a tendency to form fibre-like structures through aggregation of particles, but fibre formation was found to be disrupted by the addition of the other diastereomer, with 3:7S:R showing complete disruption of fibre formation, and consequently only particles were observed.…”

Self-Assembly of Bodipy-Derived Extended π-Systems

“…53,54 In chloroform, the molecule 10 and the polymers 1113 (Figure 5a) exhibited similar emission maximum (532 nm) when they were excited at the wavelength of the absorption maximum of the Bodipy core as well as at the π ¼ π* bands of the individual compounds. The polymers 1113 were reported to have absolute fluorescence quantum yield (Φ F ) of 80, 71, and 85%, respectively when excited at the wavelength of their respective π ¼ π* transition band.…”

“…Self-assembly of 1014 is known to form self-assembled structures with interesting morphological features ranging from particles and fibers to intertwined networks. 53,54 For instance, scanning electron microscopy (SEM) analysis of the selfassembly of 10 in THF revealed the formation of particles with nanometer to micrometer dimensions (Figure 5b). On the other hand, polymer 11 self-assembled to form particles in THF and further aggregation of the particles led to the formation of fiberlike structures (Figure 5c).…”

Aggregation enhances luminescence and photosensitization properties of a hexaiodo-BODIPY

“…BODIPYs are known to be highly emissive in solution with many molecules exhibiting fluorescence quantum yield close to unity. 16,20,[53][54][55] However, B 3 is an exception and it was observed to be negligibly fluorescent. The peculiar structure of B 3 could have contributed to its non-emissive character.…”