Synthesis of two new gem-fluoronitro containing tetranitroadamantanes and property comparison with their nitro and gem-dinitro analogues.

Two new fluorinated tetranitroadamantanes, 2,6-difluoro-2,4,4,6-tetranitroadamantane and 2,4,6,8-tetrafluoro-2,4,6,8-tetranitroadamantane, were synthesized. 2,6-Difluoro-2,4,4,6-tetranitroadamantane was prepared from 4,4-dinitroadamantane-2,6-dione by a three-step route with an overall yield of 40%. It has a slightly higher crystal density (1.787 g cm-3) than its analogue 2,2,4,4,6,6-tetranitroadamantane (1.777 g cm-3). 2,4,6,8-Tetrafluoro-2,4,6,8-tetranitroadamantane was prepared from 4,8-dihydroxyadamantane-2,6-dione by an eight-step route with an overall yield of 8%. It is notable that the replacement of one nitro group in the gem-dinitro functionality with fluorine might slightly reduce the detonation performance but improve the density and inherent steric hindrance, which makes it possible to introduce more nitro functionalities on the adamantane backbone.

Morpholine Derivative-Functionalized Carbon Dots-Based Fluorescent Probe for Highly Selective Lysosomal Imaging in Living Cells.

The development of a suitable fluorescent probe for the specific labeling and imaging of lysosomes through the direct visual fluorescent signal is extremely important for understanding the dysfunction of lysosomes, which might induce various pathologies, including neurodegenerative diseases, cancer, and Alzheimer's disease. Herein, a new carbon dot-based fluorescent probe (CDs-PEI-ML) was designed and synthesized for highly selective imaging of lysosomes in live cells. In this probe, PEI (polyethylenimine) is introduced to improve water solubility and provide abundant amine groups for the as-prepared CDs-PEI, and the morpholine group (ML) serves as a targeting unit for lysosomes. More importantly, passivation with PEI could dramatically increase the fluorescence quantum yield of CDs-PEI-ML as well as their stability in fluorescence emission under different excitation wavelength. Consequently, experimental data demonstrated that the target probe CDs-PEI-ML has low cytotoxicity and excellent photostability. Additionally, further live cell imaging experiment indicated that CDs-PEI-ML is a highly selective fluorescent probe for lysosomes. We speculate the mechanism for selective staining of lysosomes that CDs-PEI-ML was initially taken up by lysosomes through the endocytic pathway and then accumulated in acidic lysosomes. It is notable that there was less diffusion of CDs-PEI-ML into cytoplasm, which could be ascribed to the presence of lysosome target group morpholine on surface of CDs-PEI-ML. The blue emission wavelength combined with the high photo stability and ability of long-lasting cell imaging makes CDs-PEI-ML become an alternative fluorescent probe for multicolor labeling and long-term tracking of lysosomes in live cells and the potential application in super-resolution imaging. To best of our knowledge, there are still limited carbon dots-based fluorescent probes that have been studied for specific lysosomal imaging in live cells. The concept of surface functionality of carbon dots will also pave a new avenue for developing carbon dots-based fluorescent probes for subcellular labeling.