. Author manuscript; available in PMC: 2019 May 14.

Published in final edited form as: Anal Chem. 2019 Feb 6;91(4):3110–3117. doi: 10.1021/acs.analchem.8b05709

Table 1.

Calculated, Modeled, and Measured Properties of Non-NIR Fluorescent Rosol Dyes and THQ-Rosol.

Compound
E_LUMO (hartrees)^a	−0.07500	−0.07520	−0.07795	−0.07281	−0.06856
E_HOMO (hartrees)^a	−0.18814	−0.18811	−0.19086	−0.18333	−0.17245
ΔE (hartrees)	0.11314	0.11291	0.11291	0.11052	0.10389
Torsion angle N-C2’ (θ)^b	-	-	-	-	12.21°
Torsion angle N-C3’ (θ)^b	18.57°	14.86°	12.01°	7.45°	10.34°
λ_abs (nm)^c	520	524	525	540	550
λ_em (nm)^d	557	558	563	574	710
Stokes shift (nm)	37	34	38	34	160
Photostability (I/I₀)^e	0.99	0.98	0.97	0.98	0.99
ε (M⁻¹ cm⁻¹)	46,136	42,629	42,460	30,420	29,382
Φ_fl^f	0.182 ± 0.007	0.098 ± 0.001	0.048 ± 0.001	0.414 ± 0.025	0.029 ± 0.001
Brightness (M⁻¹cm⁻¹)	8.4	4.2	2.0	13	0.85
pK_a^g	4.84	4.97	4.95	5.76	5.85

DFT calculations were performed on the truncated scaffolds of each modeled fluorescent rosol dye to obtain their respective E_LUMO and E_HOMO values.

The modeled torsion angle is the offset from planarity (in degrees) of the alkyl substituent that is appended to the C2’- or C3’-nitrogen atom in relation to their respective xanthene core-based scaffold.

Measured maximum absorption wavelength of the fluorescent rosol dye (20 μM) in aqueous buffer (50 mM phosphate, 150 mM NaCl, pH 7.4).

Measured maximum emission wavelength of the fluorescent rosol dye (20 μM) upon exciting it at its respective λ_abs in aqueous buffer (50 mM phosphate, 150 mM NaCl, pH 7.4).

I0 is the measured initial fluorescence intensity of the fluorescent rosol dye and I is its measured fluorescence intensity after 30 min of continuous photoirradiation.

Φfl is the measured fluorescence quantum yield.

pK_a values were determined using 20 μM of the fluorescent rosol dye in aqueous buffer (50 mM phosphate, 150 mM NaCl, pH 7.4). Error in ^Φfl and pK_a values are ±5% based on triplicate measurements.