First-principles calculations are performed to further investigate the structure and electronic properties of (R-ClMBA)3GeI5 and (S-ClMBA)3GeI5. The atomic positions of the structures are optimized with the lattice parameters being fixed to the experimental values. After optimization and taking (R-ClMBA)3GeI5 as example, the GeI6 octahedra shows 14° tilting angle about the axis vertical to the inorganic GeI5 layers, as shown in Figure . Such tilting angle leads to the Ge-I-Ge bond angle of about 152.04° which is very close to the experimental angle 157.70°. For the other two axes of the pseudo cubic of GeI6, which lie in the GeI5 layers, there are no obvious tilting. The Ge-I bond lengths are also shown in Figure . The band structure of (R-ClMBA)3GeI5 is shown in Figure in which an indirect band gap of about 2.65 eV is presented with the VBM at (0 0 0) point and CBM at A(-0.5 0 0.5) point. We note that the calculated band gap value is in well agreement with the experimental one, i.e., 2.69 eV (see later in the text). Furthermore, the band structure with considering the spinorbital coupling (SOC) is also calculated (not shown here), however it shows very little difference with the band structure without SOC. In Figure , we show the projected density of states of (R-ClMBA)3GeI5. One can easily find that the VBM is mainly contributed by the I atoms from the GeI5 inorganic framework, while the CBM is mainly contributed by the C atoms of the organic molecules. Linear absorption spectra (see Figure ) show quite sharp edge around 420 nm without any indication of excitonic peak in agreement with the results on (R-MBA)2SnI4 and (S-MBA)2SnI4 where such behavior was correlated with the high level of structural distortion which is even greater for the present samples. The band-gap values extrapolated from the Tauc plots (Figure ) for indirect transitions are 2.69 and 2.71 eV, respectively, for (R-ClMBA)3GeI5 and (S-ClMBA)3GeI5. The CD spectra present two peaks in the range 350-460 nm, namely one centered around 371 nm and the second one around 440 nm in good agreement with the absorption edge. The presence of opposite sign CD peaks for the two samples confirm the chirality transfer from the chiral ligand ClMBA to the inorganic framework. As a matter of fact, the two chiral amines have CD spectra with a peak centered around 245 nm (see Figure ). The chiral anisotropy factor, gCD, has been calculated from the CD measurements and resulted to be around 4 × 10 -3 . It is not possible, at present, to make a direct comparison of the chiroptical properties of (R-ClMBA)3GeI5 and (S-ClMBA)3GeI5 with available data on chiral perovskites due to the fact that this is the first composition containing germanium but, more importantly, the structural motif of the present samples has not been found in any other chiral perovskite to date. However, we can report the value of the gCD for the two 1D perovskites of this