Meta-Fluors-A Unique Way To Create a 200 Da Ultrasmall Fluorophore Emitting in Red with Intense Stokes/Solvatochromic Shift: Imaging Subcellular Nanopolarity in Live Stem Cells

摘要

The smallest fluorophore reported in literature to emit in the red has a MW > 250 Da. Hereby, we report a unique way to obtain red, orange emission in ultrasmall fluorophores (DEAMB, MW = 207 Da), (DEAB, MW = 177 Da), respectively. In this exceptional concept, we explore charge transfer between meta-oriented donor-acceptor moieties in a single-benzenic fluorophore (meta-fluors). Unlike existing red-emitting small-fluorophores, our meta-fluors exhibit an intense Stokes shift (225 nm), solvatochromic shift (175 nm), and excited-state lifetime (21 ns), quite suitable for fluorescence multiplexing. Thus, from size, MW, emission maximum, Stokes shift, solvatochromic shift, excited-state lifetime, etc., points of view meta-fluors are highly advanced in comparison to para-analogues. These two meta-fluors could be employed successfully to image and measure nanopolarity of the perinuclear membrane of live stem cell. These exceptional observations will open up a new branch of developing galaxy of ultrasmall meta-fluors for various applications.