硼杂分子带:可控合成与发光功能

Boron-Doped Molecular Ribbons:Controlled Synthesis and Emission Function

硼杂分子带具有独特的电子结构和光电磁性能,然而,受限于硼原子对水氧的敏感性及其削弱芳环的成环活性,硼杂分子带的液相合成仍然极具挑战性。鉴于此,本课题组提出了共轭硼烷可控环合的方法,采用液相光化学和索尔环合反应,制备出一系列硼杂纳米分子带,不仅实现了对边缘结构和共轭长度的控制,而且调控了分子的能带结构,探索了发光性质和电荷传输功能等,从而为有机光功能材料领域提供了新材料体系,为纳米碳分子领域开辟了新研究方向。

Molecular ribbons(MRs),namely graphene nanoribbons with well-defined chemical structures,exhibit unique electronic structures and optoelectronic properties,and thus have attracted great attention in synthetic chemistry and materials science.Incorporation of the boron atom into theirπ-skeletons may enable modulation of electronic structures and physical properties by utilizing the electronic characteristics of the boron atom.However,it remains very challenging to synthesize boron-doped MRs in solution,due to the instability of the boron atoms toward moister and oxygen and the reduced cyclization activity of aromatic rings caused by the electron-deficient nature of the boron atoms.Thus,the structural construction and functional exploration of boron-doped MRs is severely hampered.Recently,our group have proposed a new strategy to construct boron-doped MRs,namely controlled cyclization of conjugated organoboranes.We synthesized a series of borondoped MRs using solution-phase photocyclization reaction,and two of them feature isomeric C68B2π-skeletons with 2.2 nm in length.We found that they have sufficient Lewis acidity,and the formed Lewis acid-based adducts display the photoinduced dual-dissociation behavior in the excited state and thus photochromism property.Moreover,despite of the highly contorted topological conformations,they exhibit hole transporting ability in organic field-effect transistors.On the other hand,we developed two new boron-doped conjugatedπ-units and then performed precise sequential cyclization reactions,affording three boron-doped MRs with controlled edges.Their band gaps and fluorescence properties were successfully modulated,and notably,the stimulated emission behavior and amplified spontaneous emission property were achieved for one boron-doped MR,demonstrating its potential as an optical-gain lasing material.These studies not only provide a new molecular system for organic optical materials,but also open a new direction for molecular carbons.