Adak Anirban, Panda Tamas, Raveendran Anju, Bejoymohandas Kochan Sathyaseelan, Asha K S, Prakasham A P, Mukhopadhyay Balaram, Panda Manas K
Department of Chemical Science, Indian Institute for Science and Educational Research Kolkata, Mohanpur 741246, Kolkata, India.
New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates, P.O. Box 129188.
ACS Omega. 2018 May 16;3(5):5291-5300. doi: 10.1021/acsomega.8b00250. eCollection 2018 May 31.
In this study, we report a synthetically simple donor-acceptor (D-A)-type organic solid-state emitter that displays unique fluorescence switching under mechanical stimuli. Orange and yellow emissive crystals of (, ) exhibit an unusual "back and forth" fluorescence response to mechanical force. Gentle crushing (mild pressure) of the orange or yellow emissive crystal results in hypsochromic shift to cyan emissive fragments (λ = 498-501 nm) with a large wavelength shift Δλ = -71 to -96 nm, while further grinding results in bathochromic swing to green emissive powder λ = 540-550 nm, Δλ = +40 to 58 nm. Single-crystal X-ray diffraction study reveals that molecules are packed by weak interactions, such as C-H···π, C-H···N, and C-H···F, which facilitate intermolecular charge transfer in the crystal. With the aid of structural, spectroscopic, and morphological studies, we established the interplay between intermolecular and intramolecular charge-transfer interaction that is responsible for this elusive mechanochromic luminescence. Moreover, we have also demonstrated the application of this organic material for chlorine gas sensing in solid state.
在本研究中，我们报道了一种合成简单的供体-受体（D-A）型有机固态发光体，其在机械刺激下表现出独特的荧光开关特性。（，）的橙色和黄色发光晶体对机械力表现出异常的“来回”荧光响应。对橙色或黄色发光晶体进行轻柔挤压（轻微压力）会导致蓝移至青色发光碎片（λ = 498 - 501 nm），波长有较大位移Δλ = -71至 -96 nm，而进一步研磨则会导致红移至绿色发光粉末（λ = 540 - 5,50 nm，Δλ = +40至58 nm）。单晶X射线衍射研究表明，分子通过弱相互作用堆积，如C-H···π、C-H···N和C-H···F，这有助于晶体中的分子间电荷转移。借助结构、光谱和形态学研究，我们确定了分子间和分子内电荷转移相互作用之间的相互作用，这种相互作用导致了这种难以捉摸的机械变色发光现象。此外，我们还展示了这种有机材料在固态氯气传感中的应用。
