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The properties of chiral donor–acceptor systems displaying CPL sign inversion are investigated in solvents of different polarity. The solvent enables control of their deexcitation pathways favoring either locally excited or charge-transfer states. 

Following previous work on helicene–porphyrin conjugates in which carbo[6]helicene are connected to zinc‐porphyrin via phenyl‐bis‐ethynyl bridges (Por(Zn)‐H[6]¹, series 1), and displaying clear exciton coupling (EC) chirality, novel carbo[6]helicenes derivatives substituted at their 2,15 positions by zinc‐porphyrin units are prepared, either through a triple bond (Por(Zn)‐H[6]², series 2), or through an alkynyl‐phenyl bridge (Por(Zn)‐H[6]³, series 3). Series 2 is also synthesized with free porphyrins or different metals [Ni(II) and Pd(II)]. Their photophysical and chiroptical properties (electronic circular dichroism and circularly polarized luminescence) are characterized, and it is examined how i) the distance between the porphyrin units and ii) the metal type impacted these properties. Experimental and theoretical analyses highlight strong responses originating from EC chirality in combination with the typical helicene‐centered optical activity. ThePor(Zn)‐H[6]²system displaying strong absorption dissymmetry factors is then selected to experimentally examine the chiral‐induced spin selectivity effect by magnetic conductive atomic force microscopy; a spin polarization of 50% is measured. 

Synthesis of two dithia[9]helicenes by means of a LED-based double photocyclization is reported. The compounds have sulfur atoms placed at the terminal rings of the helicene, and they display two alternative C 2 -symmetrical arrangements named exo (1) and endo (2). Separation of enantiomers of opposite helicity allowed the complete characterization in solution, in silico , by X-ray crystallography, and adsorbed on gold. The theoretical analysis confirms the unexpected finding that endo -dithia[9]helicene displays an experimental dissymmetry factor ( g lum ) in CPL larger than its isomer exo -dithia[9]helicene (–0.0125 vs. −0.0042). This enhanced g lum factor ranks among the largest for a helicene-type molecule. Comparison with smaller analogues, namely exo and endo -dithia[7]helicenes (10 and 11, respectively), is also presented.