Spectroscopy

FT-IR transmission spectrum

as-synthesised FeQ black precipitate / powder with small crystals · Powder

Figure S2 and Table S3 compare FeQ with quinizarin/lithiated quinizarin carbonyl-region assignments

Geometry: powder spectrum
Context: pristine framework powder
Measurement source: p002 · Figure S2 / Table S3 · Figure S2; Table S3

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
unbound-ligand carbonyl stretch absent in FeQ	carbonyl stretch of unbound quinizarin at 1638 cm-1 not observed in FeQ	—	—	SI Table Exact Reported	p002 · Figure S2 · Figure S2
lithiated quinizarin C=O shifted comparison	quinizarin C=O 1638 cm-1; lithiated quinizarin C=O 1523 cm-1	—	—	SI Table Exact Reported	p002 · Table S3 · Table S3

UV-visible absorption / Tauc analysis on Varian Cary 50 Spectrophotometer 3.0

UV-visible and optical absorption spectroscopy

as-synthesised FeQ black precipitate / powder with small crystals · Powder

Finely powdered material compressed between quartz disks; 200-1000 nm, 3000 nm min^-1 scan rate, 0.5 nm intervals, 0.1 s average time; F(R) used analogously to absorbance due to scattering

Geometry: powder compressed between two quartz disks
Context: pristine FeQ powder
Measurement source: p007 · 2.3. Characterisation of materials

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
optical band gap upper endpoint	3.3 eV upper endpoint of estimated 2.3-3.3 eV optical band-gap range	—	range endpoint; scattering limited estimate	Caption Range	p009 · 4. Results · Figure 5
optical band gap lower endpoint	2.3 eV lower endpoint of estimated 2.3-3.3 eV optical band-gap range	—	range endpoint; scattering limited estimate	Caption Range	p009 · 4. Results · Figure 5

2 measurement groups · 4 results