Electronic spectra of porphyrins in the solid state: Newly observed transitions, collective and structural effects, and protein-mimicking environments

► Specular reflectance allows spectroscopy on solid samples. ► Spectra and calculations of various solid-state porphyrins are covered in this review. ► Environmental effects are seen on single porphyrin molecules in porous network solids. ► Porphyrin ring puckering has been correlated with spectral red shift. ► The nature of electronic delocalization in phthalocyanines has been determined.