Compound characterization data — Egoshi et al., 2026

Syusuke Egoshi, Yusuke Ono, Kosuke Dodo, Mikiko Sodeoka. “Complexation-induced resonance Raman effect as a novel platform for monitoring intracellular Fe2+.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15007471/v1

Fe2+–1,10-phenanthroline complex
Resonance Raman bands	1303, 1459, and 1517 cm⁻¹
Intracellular resonance Raman signal	1517 cm⁻¹

Fe2+–2,2′-bipyridyl complex
Resonance Raman bands	1323 and 1492 cm⁻¹
Intracellular resonance Raman signal	1492 cm⁻¹

4,7-Bis((trimethylsilyl)ethynyl)-1,10-phenanthroline
Identifier	4
¹H NMR (400 MHz, CDCl₃)	δ 9.12 (d, J = 4.8 Hz, 2H), 8.35 (s, 2H), 7.72 (d, J = 4.8 Hz, 2H), 0.37 (s, 18H)
¹³C NMR (100 MHz, CDCl₃)	δ 149.9 (2C), 146.2 (2C), 129.8 (2C), 128.6 (2C), 126.0 (2C), 125.2 (2C), 105.8 (2C), 100.2 (2C), 0.0 (6C)
HRMS (FD)	Calculated for C₂₂H₂₄N₂Si₂ [M]⁺, 372.1478: found, 372.1479
Spontaneous Raman signal	2165 cm⁻¹

4,7-Diethynyl-1,10-phenanthroline
Identifier	5
¹H NMR (400 MHz, CDCl₃)	δ 9.17 (d, J = 4.4 Hz, 2H), 8.37 (s, 2H), 7.78 (d, J = 4.4 Hz, 2H), 3.75 (s, 2H)
¹³C NMR (100 MHz, CDCl₃)	δ 149.9 (2C), 145.9 (2C), 129.1 (2C), 128.8 (2C), 126.6 (2C), 125.2 (2C), 87.4 (2C), 79.2 (2C)
HRMS (FD)	Calculated for C₁₆H₈N₂ [M]⁺, 228.0687: found, 228.0688
Spontaneous Raman signal	Near 2110 cm⁻¹
Intracellular alkyne Raman-image band	2114 cm⁻¹

Fe2+ complex of 4,7-diethynyl-1,10-phenanthroline
Resonance Raman bands	1272, 1457, 1515, 1562, 1603, and 1632 cm⁻¹
UV–vis absorption upon Fe2+ coordination	strong visible-light absorption; absorption band was red-shifted and had greater absorbance intensity relative to compounds 1 and D-1
Resonance Raman upon Fe2+ coordination under 532 nm excitation	aromatic vibrational-mode enhancement was higher than for [Fe(phen)₃]²⁺; enhancement of the alkyne vibrational mode remained weak
Intracellular resonance Raman signal	1517 cm⁻¹

Solutions containing 4,7-diethynyl-1,10-phenanthroline and Cu+
Raman bands	Near 2220 cm⁻¹

3,8-Bis((trimethylsilyl)ethynyl)-1,10-phenanthroline
Identifier	7
¹H NMR (400 MHz, CDCl₃)	δ 9.19 (s, 2H), 8.32 (d, J = 1.6 Hz, 2H), 7.74 (d, J = 1.6 Hz, 2H), 0.31 (s, 18H)
¹³C NMR (100 MHz, CDCl₃)	δ 152.7 (2C), 144.2 (2C), 139.0 (2C), 128.1 (2C), 127.0 (2C), 119.9 (2C), 101.6 (2C), 100.3 (2C), 0.0 (6C)
HRMS (FD)	Calculated for C₂₂H₂₄N₂Si₂ [M]⁺, 372.1478: found, 372.1479
Spontaneous Raman signal	2165 cm⁻¹
UV–vis absorption and resonance Raman upon Fe2+ coordination	visible absorption bands and resonance Raman signals were generated

3,8-Diethynyl-1,10-phenanthroline
Identifier	8
¹H NMR (400 MHz, CD₃OD)	δ 9.07 (d, J = 2.0 Hz, 2H), 8.53 (t, J = 2.0 Hz, 2H), 7.92 (d, J = 2.0 Hz, 2H), 3.99 (s, 2H)
¹³C NMR (100 MHz, CD₃OD)	153.1(2C), 145.0 (2C), 140.7 (2C), 129.7 (2C), 128.3 (2C), 120.7 (2C), 84.1 (2C), 81.0 (2C)
HRMS (FD)	Calculated for C₁₆H₈N₂ [M]⁺, 228.0687: found, 228.0688
Spontaneous Raman signal	Near 2110 cm⁻¹
UV–vis absorption and resonance Raman upon Fe2+ coordination	Fe2+ coordination ability appeared weaker than that of compound 7 based on the absorption and Raman spectra

2,9-Bis((trimethylsilyl)ethynyl)-1,10-phenanthroline
Identifier	10
¹H NMR (400 MHz, CDCl₃)	δ 8.19 (d, J = 8.4 Hz, 2H), 7.76 (s, 2H), 7.75 (d, J = 8.4 Hz, 2H), 0.3 (s, 18H)
¹³C NMR (100 MHz, CDCl₃)	δ 145.4 (2C), 143.4 (2C), 136.2 (2C), 128.1 (2C), 127.0 (2C), 126.9 (2C), 104.5 (2C), 97.1 (2C), -0.2 (6C)
HRMS (FD)	Calculated for C₂₂H₂₄N₂Si₂ [M]⁺, 372.1478: found, 372.1478
Spontaneous Raman signal	2165 cm⁻¹
UV–vis absorption and resonance Raman upon Fe2+ addition	neither visible absorption changes nor detectable resonance Raman enhancement

2,9-Diethynyl-1,10-phenanthroline
Identifier	11
¹H NMR (400 MHz, CDCl₃)	δ 8.22 (d, J = 8.4 Hz, 2H), 7.80 (d, J = 8.4 Hz, 2H), 7.80 (s, 2H), 3.31 (s, 2H)
¹³C NMR (100 MHz, CDCl₃)	δ 145.7 (2C), 143.0 (2C), 136.4 (2C), 128.3 (2C), 127.1 (2C), 127.0 (2C), 83.6 (2C), 79.0 (2C)
HRMS (FD)	Calculated for C₁₆H₈N₂ [M]⁺, 228.0687: found, 228.0687
Spontaneous Raman signal	Near 2110 cm⁻¹
UV–vis absorption and resonance Raman upon Fe2+ addition	neither visible absorption changes nor detectable resonance Raman enhancement

1,10-Phenanthroline-d8
Identifier	D-1
C–D stretching bands	2273 and 2297 cm⁻¹

Fe2+ complex of 1,10-phenanthroline-d8
Resonance Raman bands	1272, 1440, 1470, 1550, and 1614 cm⁻¹
Intracellular resonance Raman band	1470 cm⁻¹