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European	Journal	of	Chemistry	8	(3)	(2017)	314‐316	

	

European	Journal	of	Chemistry	
ISSN	2153‐2249	(Print)	/	ISSN	2153‐2257	(Online)		2017	Atlanta	Publishing	House	LLC	‐	All	rights	reserved	‐	Printed	in	the	USA	

http://dx.doi.org/10.5155/eurjchem.8.3.314-316.1579 

	
	

	

	

European	Journal	of	Chemistry	
Journal	webpage:	www.eurjchem.com	 	

	 	 	

A	high	selective	fluorescent	sensor	for	Ni(II)	ion	in	acetonitrile	

Ya	Wei	Cao,	Xiao	Liang	Li	and	Yong	Wu	He	*	

College	of	Materials	Science	and	Engineering,	Hebei	University	of	Engineering,	Handan	056038,	P.	R.	China	

*	Corresponding	author	at:	College	of	Materials	Science	and	Engineering,	Hebei	University	of	Engineering,	Handan	056038,	P.	R.	China.		
Tel.:	+86.310.7977081.	Fax:	+86.310.8578796.	E‐mail	address:	heyongwu@hebeu.edu.cn	(Y.W.	He).	

	
	

	 	

	 	 	

COMMUNICATION	INFORMATION	 	 ABSTRACT	

	
DOI: 10.5155/eurjchem.8.3.314-316.1579	

Received:	06	May	2017	
Received	in	revised	form:	04	June	2017	
Accepted:	05	June	2017	
Published	online:	30	September	2017	
Printed:	30	September	2017

 

	 In	 this	 paper,	 a	 high	 selective	 fluorescent	 sensor	 for	 nickel	 ion	 based	 on	boron‐
dipyrromethene	(BODIPY)	has	been	studied.	Upon	addition	of	Ni(II)	ion,	the	fluorescence	of
sensor	(compound	1)	would	be	quenched,	and	the	selectivity	towards	Ni(II)	ion	over	Ag(I),
Cd(II),	 Cu(II),	 Fe(III),	 Hg(II),	 Pb(II),	 and	 Zn(II)	 is	 good	 in	 acetonitrile,	 there	 is	 almost	 no
interference	from	other	heavy	metal	ions.	The	stoichiometry	of	complexation	for	compound
1	with	Ni(II)	ion	is	1:1,	and	the	quenching	process	could	be	reversed	by	triethanolamine.	

KEYWORDS	
Sensors	
BODIPY	
Nickel	ion	
Fluorescence	
Heavy	metal	ions	
Fluorescent	sensor			

Cite	this: Eur.	J.	Chem.	2017,	8(3), 314‐316

	
1.	Introduction	
	

Nickel	is	commonly	found	in	hydrogenated	oils,	milk,	milk	
products	and	etc.	Moreover,	nickel	is	known	to	cause	diseases,	
like	 acute	 pneumonitis,	 dermatitis,	 asthma,	 lung	 etc.	 [1,2].	
Therefore,	monitoring	nickel	in	environment	is	very	important	
due	to	its	toxic	nature	and	some	conventional	techniques	such	
as	 flow	 injection	 spectrophotometry,	 flame	 and	 graphite	
furnace	atomic	absorption	spectrophotometry,	ICP‐AES,	flame	
photometry	and	ion‐selective	electrodes	have	been	developed	
for	 the	 determination	 of	 nickel.	 However,	 there	 are	 some	
drawbacks	 for	 these	 methods	 such	 as	 require	 sample	 pre‐
treatment,	 infrastructure	 backup	 and	 high	 concentration	 of	
sample,	 therefore,	 not	 very	 convenient	 for	 analysis	 of	 large	
number	of	environmental	samples	and	trace	analysis	[3].	

Fluorescent	 sensors	 are	 often	 used	 to	 detect	 many	 ions	
owing	to	their	simplicity	and	sensitivity	[4‐6].	Therefore,	many	
fluorescent	sensors	for	sensing	metal	 ions	(such	as	Zn(II)	[7],	
Cd(II)	 [8],	 Cu(II)	 [9],	 Pb(II)	 [10],	Hg(II)	 [11]	 and	Cr(III)	 [12])	
have	 been	 successfully	 designed	 and	 synthesized.	 Although	
some	 chromogenic	 sensor	 for	 Ni(II)	 ion	 have	 been	 reported	
[13],	 the	 fluorescent	 sensor	 for	Ni(II)	 ions	 is	 extremely	 rare.	
Recently,	 Chattopadhyay	 et	 al.	 [14]	 reported	 a	 fluorescent	
sensor	 for	 both	 Zn(II)	 and	Ni(II)	 ions.	 But,	 the	 drawback	 for	
this	 sensor	 is	 that	 10‐fold	 increase	 in	 fluorescence	 intensity	
caused	by	Zn(II)	ion	and	7‐fold	increase	caused	by	Ni(II)	ion	at	
pH	=	10.96.	Thus,	it	has	been	a	significant	challenge	to	develop	

a	sensitive	fluorescent	sensor	for	Ni(II)	ion.	Herein,	we	report	
a	simple	selectively	fluorescent	sensor	for	Ni(II)	 ion	based	on	
boron‐dipyrromethene	(BODIPY)	in	acetonitrile	(Scheme	1).	
	
2.	Experimental	
	
2.1.	Instrumentation	

	
All	 the	 commercial	 reagents	 and	 solvents	 were	 used	

without	further	purification.	The	1H	and	13C	NMR	spectra	were	
collected	on	Jeol	JNM‐AL300	spectrometer	at	300	MHz	and	75	
MHz,	 respectively.	HRMS	 spectra	were	 recorded	on	 Jeol	 JMS‐
700	spectrometer.	UV‐vis	absorption	spectra	were	obtained	on	
a	Shimadzu	UV‐3100	spectrophotometer.	Fluorescence	spect‐
ra	 were	 recorded	 with	 a	 FL‐4500	 spectrofluorophotometer.	
Stock	 solutions	 (1.00	 mM)	 of	 metal	 salts	 were	 prepared	 in	
CH3CN.	Stock	solutions	of	free	1	 (1.00	mM)	were	prepared	 in	
CH3CN.	

	
2.2.	Synthesis	

	
1,	3,	5,	7‐Tetramethyl‐8‐(4’‐aminophenyl)‐4,	4‐difluoro‐4‐

bora‐3a,4a‐diaza‐s‐indacence	[15]	(0.1017	g,	0.3	mmol)	and	2‐
pyridinecarbaldehyde	 (0.0321	 g,	 0.3	 mmol)	 were	 placed	 in	
ethanol,	and	the	solution	was	refluxed	under	nitrogen	for	24	h.	
The	organic	solvent	was	removed	in	vacuum.		

	



Cao	et	al.	/	European	Journal	of	Chemistry	8	(3)	(2017)	314‐316	 315	
 

	

 
	

Scheme	1
	
	
The	crude	product	was	purified	by	recrystallization	to	give	

the	title	compound	as	an	orange	solid	(0.1040	g,	80.8%).	N‐(4‐
(5,5‐difluoro‐1,	 3,	 7,	 9‐tetramethyl‐5H‐4l4,	 5l4‐dipyrrolo[1,	 2‐
c:2',	1'‐f][1,	3,	2]diazaborinin‐10‐yl)phenyl)‐1‐(pyridin‐2‐
yl)methane‐mine	 (1):	 1H	NMR	(300	MHz,	CDCl3,	δ,	ppm):	1.46	
(s,	6H,	CH3),	2.57	(s,	6H,	CH3),	6.00	(s,	2H,	Ar‐H),	7.33	(d,	2H,	J	=	
8.4	Hz,	Ar‐H),	7.41	(d,	3H,	J	=	8.4	Hz,	Ar‐H),	7.86	(t,	1H,	J	=	7.8	
Hz,	Ar‐H),	8.23	(d,	1H,	J	=	7.8	Hz,	Ar‐H),	8.67	(s,	1H,	NC‐H),	8.75	
(d,	1H,	J	=	4.8	Hz,	Ar‐H).	13C	NMR	(75	MHz,	CDCl3,	δ,	ppm)	14.6,	
121.2,	 121.9,	 122.0,	 125.5,	 129.0,	 133.3,	 136.8,	 143.1,	 149.9,	
151.7,	 154.2,	 155.5,	 161.7.	 HRMS	 (EI,	 m/z	 (%))	 calcd.	 for	
C25H23BF2N4	[M+],	428.1984;	found	428.1976.	
	
3.	Results	and	discussion		

	
Initially,	metal	ion	selectivity	was	examined	in	acetonitrile.	

Changes	of	the	fluorescence	properties	of	compound	1	caused	
by	 various	 metal	 ions	 including	 Ag(I),	 Cd(II),	 Cu(II),	 Fe(III),	
Hg(II),	 Ni(II),	 Pb(II),	 and	 Zn(II)	 (10	 equiv.)	 were	 measured	
(Figure	1).	Only	Ni(II)	ion	produced	significant	changes	in	the	
fluorescent	 spectra	 of	 compound	 1	 (quenched	 95%	 by	 10	
equiv.)	 and	 Fe(III)	 ion	 caused	 fluorescence	 intensity	 of	
compound	1	quenching	a	little	(quenched	24%	by	10	equiv.).	

	

	
	
Figure	1.	Fluorescence	spectra	of	compound	1	(10	µM)	in	acetonitrile	in	the	
presence	of	Ni(II)	ion	and	other	metal	ions	(10	equiv.,	respectively).	

		
Figure	 2	 depicted	 the	 results	 of	 competition	 experiment	

for	compound	1.	As	shown	 in	Figure	2,	only	Fe(III)	showed	a	
little	 interference	 and	 other	 metal	 ions	 showed	 almost	 no	
change	or	a	little	enhancement	in	the	presence	of	compound	1	
and	Ni(II)	 ion.	 That	 proves	 the	 selectivity	 of	 compound	1	 to	
Ni(II)	is	good	over	other	heavy	metal	ions.	

The	 titration	 of	 fluoroionophore	 (1)	 (10	 µM)	 in	 CH3CN	
with	Ni(II)	 ion	was	also	studied.	Figure	3	exhibited	a	gradual	
decrease	 in	 the	 fluorescence	 intensity	 (507	 nm)	 with	
increasing	 concentration	 of	Ni(II)	 ion	 between	 0	 and	 10	 µM.	
That	 indicates	 a	 1+1	 stoichiometry	 of	 complexation	 for	
compound	1	with	Ni(II)	ion.	

	

	
	
Figure	2.	Fluorescence	 response	 of	 compound	1	 to	 various	metal	 ions	 in	
acetonitrile.	 Bars	 represent	 the	 final	 integrated	 fluorescence	 response	 (F)	
over	the	initial	integrated	emission	(F0).	First	row:	Ni(II)	+	other	metal	ions;	
Second	row:	only	metal	ion.	
	

	
	
Figure	3.	Fluorescence	response	of	compound	1	(10	µM)	to	Ni(II)	in	CH3CN	
(2	mL),	the	spectra	show	correspond	to	free	Ni(II)	concentrations	between	0	
and	10	equiv.	in	acetonitrile.	

	
To	 examine	 the	 reversibility	 of	 compound	 1,	 excess	 of	

triethanolamine	was	added	to	the	compound	1‐Ni(II)	complex	
in	CH3CN.	As	a	result,	the	solution	showed	strong	fluorescence	
intensity	 after	 addition	of	 triethanolamine,	 indicated	 that	 the	
compound	 1‐Ni(II)	 complex	 could	 be	 reversed	 by	
triethanolamine	(Figure	4).	
	



316	 Cao	et	al.	/	European	Journal	of	Chemistry	8	(3)	(2017)	314‐316	
	

	
	
Figure	4.	 Fluorescence	 spectra	 of	 compound	1	 to	Ni(II)	 in	 CH3CN	 (2	mL),	
triethanolamine	can	increase	fluorescence	intensity	of	the	complex.	
	
4.	Conclusion	

	
In	 conclusion,	 we	 demonstrated	 a	 simple	 fluorescent	

sensor	 for	 Ni(II)	 ion	 in	 acetonitrile.	 The	 selectivity	 towards	
Ni(II)	 ion	 is	 good	 over	 Ag(I),	 Cd(II),	 Cu(II),	 Fe(III),	 Hg(II),	
Pb(II),	 and	 Zn(II)	 ions,	 almost	 no	 interference	 from	 other	
heavy	metal	ions.		
	
Acknowledgements	
	

This	work	was	 supported	 by	 the	Research	 Foundation	 of	
Department	of	Education	of	Hebei	Province,	P.	R.	China	(Grant	
No.	QN2016173),	 the	Research	Foundation	of	Administration	
of	Science	and	Technology	of	Handan,	P.	R.	China	(Project	No:	
1629209045‐4)	 and	 Foundations	 of	 Hebei	 University	 of	
Engineering.	
	
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