Cherumukkil Sandeep, Ghosh Samrat, Praveen Vakayil K, Ajayaghosh Ayyappanpillai
Photosciences and Photonics Section , Chemical Sciences and Technology Division , CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST) , Thiruvananthapuram-695019 , India . Email:
Academy of Scientific and Innovative Research (AcSIR) , CSIR-NIIST Campus , Thiruvananthapuram-695019 , India.
Chem Sci. 2017 Aug 1;8(8):5644-5649. doi: 10.1039/c7sc01696d. Epub 2017 Jun 8.
We report an unprecedented strategy to generate and amplify near-infrared (NIR) emission in an organic chromophore by mechanical stress or gelation pathways. A greenish-yellow emitting film of π-extended , obtained from -decane, became orange-red upon mechanical shearing, with a 15-fold enhancement in NIR emission at 738 nm. Alternatively, a DMSO gel of exhibited a 7-fold enhancement in NIR emission at 748 nm with a change in emission color from yellow to orange-red upon drying. The reason for the amplified NIR emission in both cases is established from the difference in chromophore packing, by single crystal analysis of a model compound (), which also exhibited a near identical emission spectrum with red to NIR emission (742 nm). Comparison of the emission features and WAXS and FT-IR data of the sheared -decane film and the DMSO xerogel with the single crystal data supports a head-to-tail slipped arrangement driven by the N-H···F-B bonding in the sheared or xerogel states, which facilitates strong exciton coupling and the resultant NIR emission.
我们报道了一种前所未有的策略，通过机械应力或凝胶化途径在有机发色团中产生并放大近红外（NIR）发射。从正癸烷获得的π-扩展的黄绿色发光薄膜，在机械剪切后变为橙红色，在738 nm处的近红外发射增强了15倍。另外，的二甲基亚砜凝胶在748 nm处的近红外发射增强了7倍，干燥后发射颜色从黄色变为橙红色。通过对模型化合物（）的单晶分析，从发色团堆积的差异确定了两种情况下近红外发射放大的原因，该模型化合物也表现出几乎相同的发射光谱，从红色到近红外发射（742 nm）。将剪切后的正癸烷薄膜和二甲基亚砜干凝胶的发射特征与广角X射线散射（WAXS）和傅里叶变换红外光谱（FT-IR）数据与单晶数据进行比较，支持了在剪切或干凝胶状态下由N-H···F-B键驱动的头对尾滑动排列，这有利于强激子耦合和由此产生的近红外发射。
