Electronic Supporting Information A Ratiometric Fluorescent Probe for Detection of Biogenic Primary Amines with Nanomolar Sensitivity

All the chemicals except ANH (8) were purchased from commercial sources and used as received without any further purification. Tryptamine, Phenetthyleneamine, 1,6-Diaminohexane and Spermidine were purchased from Alfa-aesar, and 1,3-Diaminopropane, Butylamine, Diethylamine, Diisopropylamine, Triethylamine, 1,4-Butanediamine and Diisopropylethylamine from Spectrochem. The solvents used for spectroscopic measurements were of spectroscopy grade and purchased from Sisco Research Laboratory (SRL), India. All the experiments were carried out at (298 ± 2) K.

grade and purchased from Sisco Research Laboratory (SRL), India.All the experiments were carried out at (298 ± 2) K.

(a) Steady-State Measurements
Steady state absorption measurements were done with Shimadzu UV-spectrophotometer using 10 mm path length quartz cuvettes.All steady state fluorescence measurements were carried out in DMA as a solvent using HORIBA Jobin Yvon Fluorimax-4 Fluorimeter.A dilute solution of ANH 3.6 µM was taken for all the measurements to keep the absorption value low to avoid inner filter effect.Fluorescence spectra for the titration experiments were recorded using 10 mm path length quartz cuvette in the region from 400 nm to 650 nm range by exciting at 385 nm with excitation slit 3 nm and emission slits with a width of 3 nm for all the measurements.For the titration experiments in case of primary amines, successive data points were recorded giving a 5 min interval after each and every amine addition, and for secondary and tertiary amines the intervals were 15 minutes.For kinetic measurements initially a 3.6 µM solution of ANH in DMA Electronic Supplementary Material (ESI) for Analyst.This journal is © The Royal Society of Chemistry 2015 was placed in a 10 mm path length quartz cuvette, excited at 385 nm and the emission intensity was recorded at 575 nm wavelength in kinetics mode for 1 minute , then amine solution was added in stirring condition and kinetics was measured for required time frame.All the experiments were carried out at room temperature (298 K).

(b) X-ray crystallography:
Suitable crystals for X-ray crystallography were obtained by slow evaporation of a solution of ANH in DCM and Hexane solvent mixture (9:1).Single-crystal X-ray diffraction data were collected using a Bruker SMART APEX II CCD diffractometer with graphite monochromated Mo K α (λ = 0.71073 Å) radiation at 218 K.    From the structure of ANH it is evident that the carbonyl carbon centre at a position (as mentioned above in the scheme ) is less electrophilic due to participating in direct conjugation, as it is situated at para position with respect to the N,N-dimethylamine functional group, than the carbonyl carbon centre at the b position.So, a favorable attack of the primary amine group at the carbonyl carbon centre at b, leads to the major product (A) to be formed than (B) with ca.2:1 ratio.Compound 6 1 H NMR

Final 1 (
Scheme 1 Fig S2 (a) Titration of 3.6 µM ANH with 1,4-Butanediamine (b) Ratiometric plot of titration using OD at two different wavelengths, inset shows the changes in OD at selected wavelengths

Fig S18 :Fig S20 :
Fig S18: NMR spectra of regioisomeric products obtained after the reaction of ANH with Butylamine in CDCl 3 (a) aromatic part and (b) aliphatic part; from the integration ca.2:1 ratio of the products are obtained.

Table S1 .
Crystal data and structure refinement parameters of ANH

Table S2 :
Comparison of reported methods related to detection of biogenic primary amines