Addressing fluorescence and liquid crystal behaviour in multi-mesogenic BODIPY materials
Addressing fluorescence and liquid crystal behaviour in multi-mesogenic BODIPY materials
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DOI：
10.1039/c0nj00990c
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发表时间：
2011-01-01
影响因子：
3.3
通讯作者：
Boyle, Ross W.
中科院分区：
文献类型：
--
作者：
Benstead, Michael;Rosser, Geraldine A.;Boyle, Ross W.
合成了两个系列的含介晶取代基的BODIPY（4，4 ′-difluoro-3a，4a-diaza-s-indacene），并对其荧光和自组装行为进行了观察和表征。为了诱导对液晶性的强烈偏好，两个介晶单元已连接到每个荧光团。这些化合物通过微波辅助Suzuki偶联反应以中等产率制备。采用两种不同但相关的介晶，但发现只有一个系列表现出液晶中间相的形成。通过差示扫描量热法（DSC）和光学偏振显微镜（OPM）观察到的单致性α相，通过在不同的温度范围内，这取决于烷基取代的荧光团的程度。由于BODIPY 8-苯基环的旋转限制，增加烷基取代引起荧光量子产率的逐渐增加，然而，这也破坏了介晶相的形成，从而导致表现出中间相的温度范围减小。制备的化合物的大的支化结构使它们在均相和各向同性液相中都具有高粘度。由于高粘度，只能在几个小时的退火后观察到α相的纹影织构。
Two series of BODIPYs (4,4'-difluoro-3a, 4a-diaza-s-indacene) bearing mesogenic substituents have been synthesised and their fluorescent and self-assembly behaviour has been observed and characterised. In order to induce a strong preference for liquid crystallinity, two mesogenic units have been attached to each fluorophore. The compounds were prepared by microwave-assisted Suzuki couplings in moderate yields. Two different, but related, mesogens were employed but only one series was found to exhibit the formation of liquid crystal mesophases. Monotropic nematic phases, observed by differential scanning calorimetry (DSC) and optical polarising microscopy (OPM), were adopted over varying temperature ranges depending on the degree of alkyl substitution on the fluorophore. Increasing alkyl substitution caused a gradual increase in fluorescence quantum yield due to rotational restriction of the BODIPY 8-phenyl ring, however, this also disrupted the formation of the nematic phase causing a reduction in the temperature range over which the mesophase was exhibited. The large, branched structure of the compounds prepared caused them to have a high viscosity in both the nematic and isotropic liquid phase. Due to the high viscosity, the Schlieren texture of the nematic phase could only be observed after several hours annealing.