Zinc chloride

1-Nitroso-2-naphthol, zinc chloride, (2-bromoethyl)benzene, 2,3,3-trimethylindolenine,
and triethylamine were purchased from Tokyo Chemical Industry (TCI).
Tetrahydrofuran, acetonitrile, dichloromethane, and ethanol were obtained
from Honeywell Burdick & Jackson (B&J). Metal ions including
Na⁺, K⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sn²⁺, Pb²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Hg²⁺ were obtained from Sigma-Aldrich as
chloride salts. All reagents were of analytical grade and used as
received unless stated otherwise. Deionized water (DI) was used for
all experiments. Analytical thin-layer chromatography (TLC) was performed
on Kieselgel F₂₅₄ pre-coated aluminum TLC plates obtained
from EM Science. Visualization was performed with a 254 nm ultraviolet
lamp. Column chromatography was carried out with Merck silica gel
60 (230–400 mesh ASTM). UV/vis absorption spectra were measured
on a Shimadzu (UV-1800) spectrophotometer at ambient temperature.
The path length of a quartz cell was 1 cm. ¹H NMR (500
MHz) and ¹³C NMR (125 MHz) spectra with entire proton decoupling
were recorded on a Bruker AVANCE 500 NMR spectrometer, and chemical
shifts in ppm were quoted relative to the residual signals of deuterated
solvents. High-resolution mass spectra were recorded using a Bruker
micrOTOF mass spectrometer (ESI-TOF) and reported with ion mass/charge
(m/z) ratios as values in atomic mass units.