Compound characterization data — Bartnik et al., 2026

Aleksander Bartnik, Justin Chen, Dipankar Barpuzary, and Seunghyun Sim. “Reversible electrochromic materials fueled by Shewanella oneidensis.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15008039/v1

The generic NMR decoration-calculation method and its agreement with reaction stoichiometry were not retained

L-histidine-substituted perylene diimide with Shewanella oneidensis in phosphate-buffered saline containing 20 mM sodium lactate under a nitrogen atmosphere
Aqueous-solution state at 24 mM	A hydrogel encasing S. oneidensis was observed; the gel remained invertible
UV/Vis spectrum of 50 µM H-PDI after overnight incubation	Peaks at 724 nm and 816 nm, characteristic of the radical anion; the spectra are labeled “H-PDI + S. oneidensis”, 0 min, and Overnight, with the two long-wavelength features annotated “Radical anion”

H-PDI
¹H NMR (600 MHz, DMSO-d₆ + TFA)	δ 14.48 (s, br, 2H), 14.18 (s, br, 2H), 8.96 (s, 2H), 8.93 (d, 7.7 Hz, 4H), 8.56 (d, 7.5 Hz, 4H), 7.46 (s, 2H), 5.85 (dd, 4.3, 9.6 Hz, 2H), 3.71 (dd, 4.1, 15.7 Hz, 2H), 3.44 (dd, 9.8, 15.7 Hz, 2H); peaks marked with an asterisk are H₂O and DMSO at 6.16 and 2.50 ppm, respectively; 2 µL TFA was added to improve peak resolution in NMR sample, also resulting in shift of H₂O peak

Benzyl viologen dibromide (BnV)
¹H NMR (600 MHz, DMSO-d₆)	δ 9.52 (d, 6.5 Hz, 4H), 8.74 (d, 6.5 Hz, 4H), 7.61 (d, 7.2 Hz, 4H), 7.42-7.51 (m, 6H), 5.95 (s, 4H); peaks labeled with asterisks are H₂O and DMSO at 3.33 and 2.50 ppm, respectively

Mono-substituted benzyl viologen bromide
¹H NMR (500 MHz, DMSO-d₆)	δ 9.36 (d, 6.8 Hz, 2H), 8.87 (d, 6.1 Hz, 2H), 8.64 (d, 6.8 Hz, 2H), 8.01 (d, 6.2 Hz, 2H), 7.59 (d, 6.6 Hz, 2H), 7.40-7.50 (m, 3H), 5.89 (s, 2H); peaks labeled with asterisks are H₂O and DMSO at 3.33 and 2.50 ppm, respectively

Benzyl/propylamine viologen dibromide (BnPrV)
¹H NMR (500 MHz, DMSO-d₆)	δ 9.57 (d, 6.9 Hz, 2H), 9.43 (d, 6.9 Hz, 2H), 8.82 (d, 7.0 Hz, 2H), 8.80 (d, 7.0 Hz, 2H), 7.91 (s, br, 3H), 7.63 (d, 6.5 Hz, 2H), 7.41-7.51 (m, 3H), 5.98 (s, 2H), 4.81 (t, 7.1 Hz, 2H), 2.86-2.96 (m, 2H), 2.30 (quintet, 7.2 Hz, 2H); peaks labeled with asterisks are H₂O and DMSO at 3.33 and 2.50 ppm, respectively
Mass spectrometry [M•-H•]⁺	Calculated Mass for C₂₀H₂₃N₃ [M•-H•]⁺: 304.1814. Found: 304.1818. Mass represents the radical cation with the loss of a hydrogen atom

Mono-substituted ethyl viologen bromide
¹H NMR (500 MHz, DMSO-d₆)	δ 9.24 (d, 6.8 Hz, 2H), 8.87 (d, 6.1 Hz, 2H), 8.63 (d, 6.7 Hz, 2H), 8.04 (d, 6.1 Hz, 2H), 4.67 (q, 7.3 Hz, 2 H), 1.58 (t, 7.3 Hz, 3H); peaks labeled with asterisks are H₂O and DMSO at 3.33 and 2.50 ppm, respectively

Ethyl/propylamine viologen (EtPrV)
¹H NMR (400 MHz, DMSO-d₆)	δ 9.43 (d, 4.9 Hz, 4H), 8.86 (d, 6.7 Hz, 2H), 8.81 (d, 6.6 Hz, 2H), 7.90 (s, br, 3H), 4.81 (t, 7.0 Hz, 2H), 4.74 (q, 7.2 Hz, 2H), 2.85-2.97 (m, 2H), 2.30 (quintet, 7 Hz, 2H), 1.61 (t, 7.3 Hz, 2H); peaks labeled with asterisks are H₂O, MeOH, and DMSO at 3.33, 3.17, and 2.50 ppm, respectively
Mass spectrometry [M•-H•]⁺	Calculated Mass for C₁₅H₂₁N₃ [M•-H•]⁺: 242.1657. Found: 242.1656. This mass represents the radical cation with the loss of a hydrogen atom

5 % BnPrV-Alg
¹H NMR (400 MHz, D₂O)	δ 9.18 (s, 4H), 8.58 (s, 4H), 7.53 (s, 5H), 5.94 (s, 2H), 3.50-4.35 (m, 61 H), 3.18 (s, 2H), 2.50 (s, 2H); resonance labeled “e” on structure is expected to be hidden under residual solvent peak and thus not reported; peaks marked with asterisks are HOD, MeOH, DMSO, and acetone at 4.79, 3.35, 2.88, and 2.23, respectively

10 % BnPrV-Alg
¹H NMR (400 MHz, D₂O)	δ 9.18 (s, 4H), 8.58 (s, 4H), 7.54 (s, 5H), 5.95 (s, 2H), 3.46-4.34 (m, 24 H), 3.18 (s, 2H), 2.50 (s, 2H); resonance labeled “e” on structure is expected to be hidden under residual solvent peak and thus not reported; peaks marked with asterisks are HOD, MeOH, DMSO, and acetone at 4.79, 3.35, 2.89, and 2.23, respectively

20 % BnPrV-Alg
¹H NMR (400 MHz, D₂O)	δ 9.18 (d, 5 Hz, 4H), 8.59 (d, 6.6, 2H), 8.57 (d, 6.8 Hz, 2H), 7.54 (s, 5H), 5.94 (s, 2H), 3.46-4.32 (m, 13 H), 3.18 (t, 8 Hz, 2H), 2.50 (q, 6.7 Hz, 2H); the 8.59 ppm doublet is printed without a unit for 6.6; resonance labeled “f” on structure is expected to be hidden under residual solvent peak and thus not reported; peaks marked with asterisks are HOD, MeOH, DMSO, and acetone at 4.79, 3.36, 2.89, and 2.23, respectively

10 % EtPrV-Alg
¹H NMR (400 MHz, D₂O)	δ 9.16 (s, 4H), 8.59 (s, 4H), 3.48-4.37 (m, 24 H), 3.19 (s, 2H), 2.51 (s, 2H), 1.71 (s, 3H); resonance labeled “c” on structure is expected to be hidden under residual solvent peak and thus not reported; peaks marked with asterisks are HOD, MeOH, DMSO, and acetone at 4.79, 3.35, 2.89, and 2.23, respectively

Benzyl viologen dibromide with Shewanella oneidensis in phosphate-buffered saline containing 20 mM sodium lactate under a nitrogen atmosphere
UV/Vis spectra of 50 µM BnV before and after incubation	The spectra are labeled “BnV w/ S. oneidensis”, 0 min, and 120 min, and the 120 min spectrum is annotated “radical cation”; the prose describes the appearing peaks as corresponding to the radical anion, most strongly visible at 399 nm, and states that this peak location matched the results of chemical reduction of these viologens with sodium dithionite

Ethyl viologen dibromide with Shewanella oneidensis in phosphate-buffered saline containing 20 mM sodium lactate under a nitrogen atmosphere
UV/Vis spectra of 50 µM EtV	No changes in the UV/Vis spectra were observed; the spectra are labeled 0 min and 120 min

Asymmetric ethyl propylamine viologen with Shewanella oneidensis and lactate under anaerobic conditions
UV/Vis spectrum of 50 µM EtPrV	Some peaks emerged after 60 min, but the spectral shape was not consistent with those of the other reduced viologen species; the spectra are labeled “EtPrV w/ S. oneidensis”, 0 min, and 60 min

Asymmetric benzyl propylamine viologen with Shewanella oneidensis and lactate under anaerobic conditions
UV/Vis spectrum of 50 µM BnPrV	A clear peak for the reduced viologen species was observed after 60 min; the spectra are labeled “BnPrV w/ S. oneidensis”, 0 min, and 60 min

Small-molecule viologen species
Cyclic voltammetry	The measurements showed the expected trend: the reduction potential of BnPrV lies between that of BnV and those of the two alkyl viologens, EtPrV and EtV
Measurement conditions	Ossila potentiostat and Ossila Electrochemistry software; the standard platinum working electrode, aqueous Ag/AgCl reference electrode, and platinum counter electrode from Ossila were used in a standard three-neck cell; 5-10 mM viologen in 200 mM phosphate buffer at pH 7; 10 mV/s scan rate after purging with N₂ for 30 min, with N₂ flow continued through the cell headspace

EtPrV-decorated sodium alginate with Shewanella oneidensis and lactate under anaerobic conditions
Decoration	10 %, as determined by NMR
UV/Vis spectra of 100 µM viologen and 1 mM uronate monomer	No clear change associated with viologen reduction was observed; the spectra are labeled “EtPrV-Alg w/ S. oneidensis”, 0 min, and 60 min

BnPrV-decorated sodium alginate with Shewanella oneidensis and lactate under anaerobic conditions
Decoration	10 %, as determined by NMR
UV/Vis spectra of 100 µM viologen and 1 mM uronate monomer	A clear emergence of the characteristic peaks for the reduced viologen was observed; the resulting peaks matched those from chemical reduction of the polymers; the spectra are labeled “BnPrV-Alg w/ S. oneidensis”, 0 min, and 60 min

Calcium-crosslinked BnPrV-Alg hydrogel beads encasing Shewanella oneidensis
Composition	10 % decorated BnPrV-Alg at 20 mg/mL with a saturated S. oneidensis culture; the page 7 caption prints the concentration unit as “mg/ml”
Rheology	Storage moduli of a few kPa, with storage modulus higher than loss modulus across all tested frequencies; an 8 mm parallel-plate geometry was used, amplitude sweeps were performed at 10 rad/s to determine the linear viscoelastic range before frequency sweeps, and 0.5 % strain amplitude was used at 25 °C