Synthesis and chemosensitivity of a new iminium salt toward a cyanide anion.

Rao, Boddu Ananda,Lee, Jae-Young,Son, Young-A Pergamon 2014 Spectrochimica acta. Part A, Molecular and biomole Vol.127 No.-

<P>A short, high-yielding route to pyranylidene Iminium (Imi) salts using a new pyrylium salt reaction between N,N-Dimethylformamide (DMF) and acetic anhydride is reported. The Imi salt-sensing behavior toward various anions has been investigated using UV-Visible spectroscopy. The Imi salt demonstrates high selectively for CN(-) when various other anions, such as CN(-), Cl(-), Br(-), I(-), SCN(-), ClO4(-), NO3(-), HSO4(-), PF6(-) and N3(-), are present because it is highly reactive towards nucleophiles. The selective detection of CN(-) with the Imi unit gave rise to a significant hypochromic shift in the CH3CN solution at λmax=444nm and 423nm and creation of new peak at 252nm. These studies indicated that CN(-) had high affinity toward Imi, forming a 1:1 complex; this observation agrees with the current understanding of these materials.</P>

Synthesis of a novel pyrylium salt with chemoselectivity to a cyanide anion

Rao, Boddu Ananda,Lee, Jae-Young,Son, Young-A Taylor Francis 2015 Supramolecular chemistry Vol.27 No.3

A highly selective dual-channel Cu²⁺ and Al³⁺ chemodosimeter in aqueous systems: Sensing in living cells and microfluidic flows

Kim, Hyungjoo,Rao, Boddu Ananda,Jeong, Jong Woo,Mallick, Sudipta,Kang, Sung-Min,Choi, Joon Sig,Lee, Chang-Soo,Son, Young-A. Elsevier 2015 Sensors and actuators. B Chemical Vol.210 No.-

<P><B>Abstract</B></P> <P>The design and development of fluorescent chemosensors have recently been the focus of considerable attention for the sensitive and specific detection of environmentally and biologically relevant metal ions in aqueous solutions and in living cells. Herein, we report photophysical results for a 1<I>H</I>-pyrrole-2-carboxaldehyde-substituted rhodamine 6G derivative (RCS) that possesses specific binding affinity toward Al<SUP>3+</SUP> and Cu<SUP>2+</SUP> at micromolar concentration levels. In an <I>N</I>,<I>N</I>-dimethylformamide (DMF) and water (v/v=2/8) medium, the RCS chemosensor exhibits a substantially enhanced absorbance intensity at 532nm and a color change from colorless to pink for Cu<SUP>2+</SUP>; it also exhibits significant “off–on” fluorescence at 557nm, accompanied by a color change from colorless to fluorescent-yellow upon binding to Al<SUP>3+</SUP>. The RCS sensor exhibits extremely high fluorescence enhancement upon complexation with Al<SUP>3+</SUP>, and it can be used as a “naked eye” sensor. Through fluorescence titration at 557nm, we confirmed that RCS exhibits a fluorescence response with a remarkable enhancement in emission intensity resulting from the complexation between RCS and Al<SUP>3+</SUP>, whereas no emission appeared in the case of competitive metal ions (Cu<SUP>2+</SUP>, Al<SUP>3+</SUP>, Li<SUP>+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP>, Cs<SUP>+</SUP>, Mg<SUP>2+</SUP>, Ca<SUP>2+</SUP>, Fe<SUP>2+</SUP>, Co<SUP>2+</SUP>, Ag<SUP>+</SUP>, Zn<SUP>2+</SUP>, Cd<SUP>2+</SUP>, Hg<SUP>2+</SUP> and Pb<SUP>2+</SUP>) in a DMF and water (v/v=2/8) solution. The reversible ring-opening mechanism of the rhodamine spirolactam induced by Al<SUP>3+</SUP>/Cu<SUP>2+</SUP> binding and the 1:1 stoichiometric structure between RCS and Al<SUP>3+</SUP> were adequately supported by Job-plot evaluation, optical titration and FT-IR analysis. The lowest detection limit for Al<SUP>3+</SUP> is 3.20×10<SUP>6</SUP> M<SUP>−1</SUP> in a DMF and water (v/v=2/8) solution. Al<SUP>3+</SUP>-induced chelation-enhanced fluorescence (CHEF) is associated with spirolactam ring opening of the rhodamine unit. Finally, RCS was successfully applied for the bio-imaging of Al<SUP>3+</SUP> in living HeLa cells and for fluorescence imaging of a microfluidic system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The dual mode sensor RCS for Cu<SUP>2+</SUP> and Al<SUP>3+</SUP> has developed based on rhodamine 6G derivative. </LI> <LI> The sensing properties of RCS originated due to its spiro-lactam ring system. </LI> <LI> The RCS-metal complex structure was confirmed via FT-IR studies. </LI> <LI> RCS was also studied for its potential application to bio-imaging and microfluidic systems. </LI> </UL> </P>

“Turn-on” fluorescent and colorimetric determination of Cu2+ ions in aqueous media based on a Rhodamine-N-phenyl Semicarbazide derivative

Park, Junemin,Rao, Boddu Ananda,Son, Young-A 한국섬유공학회 2015 Fibers and polymers Vol.16 No.5

A highly selective fluorescent chemosensor for Hg²⁺ based on a squaraine–bis(rhodamine-B) derivative: Part II

Lee, Sehoon,Rao, Boddu Ananda,Son, Young-A Elsevier 2015 Sensors and actuators. B Chemical Vol.210 No.-

<P><B>Abstract</B></P> <P>Herein, we report an effective strategy based on coordination-induced signaling by introducing a rhodamine B group linkage into squaraine–diamine dyads as a reversible switch. The optimized design, synthesis and application of a new optical squaraine–bis(rhodamine-B) chemosensor (<B>SRB</B>) as an ‘off–on’ fluorescent probe for the detection of Hg<SUP>2+</SUP> ions were investigated. <B>SRB</B> exhibited high selectivity toward Hg<SUP>2+</SUP> in the presence of various metal ions, such as Al<SUP>3+</SUP>, Ag<SUP>+</SUP>, Co<SUP>2+</SUP>, Cs<SUP>+</SUP>, Cu<SUP>2+</SUP>, Fe<SUP>3+</SUP>, K<SUP>+</SUP>, Li<SUP>+</SUP>, Mg<SUP>2+</SUP>, Na<SUP>+</SUP>, Ni<SUP>2+</SUP>, Pb<SUP>2+</SUP>, and Zn<SUP>2+</SUP>, and the resulting complex [<B>SRB</B>–Hg<SUP>2+</SUP>] was investigated using UV–vis and fluorescence spectroscopy in acetonitrile (CH<SUB>3</SUB>CN). The ‘off–on’ fluorescence and color signal change of the probe are based on a Hg<SUP>2+</SUP>-triggered domino reaction that employs the open-ring form of rhodamine spirolactam to regain the conjugated system of the rhodamine skeleton. The mechanism for the opening of the rhodamine spirolactam ring induced by Hg<SUP>2+</SUP> binding and the 1:1 stoichiometric structure of <B>SRB</B> and Hg<SUP>2+</SUP> were confirmed using a Job's plot estimation, optical titration and FT-IR. Subsequently, a <B>SRB</B>–Hg<SUP>2+</SUP> complex chemosensor was employed to detect CN<SUP>−</SUP> in the presence of different anions, such as Br<SUP>−</SUP>, CH<SUB>3</SUB>COO<SUP>−</SUP> or AcO<SUP>−</SUP>, Cl<SUP>−</SUP>, ClO<SUB>4</SUB> <SUP>−</SUP>, F<SUP>−</SUP>, HPO<SUB>4</SUB> <SUP>−</SUP>, HSO<SUB>4</SUB> <SUP>−</SUP>, I<SUP>−</SUP>, N<SUB>3</SUB> <SUP>−</SUP>, NO<SUB>3</SUB> <SUP>−</SUP>, PF<SUB>6</SUB> <SUP>−</SUP> and SCN<SUP>−</SUP>, in acetonitrile. In addition, this sensor exhibited highly selective and sensitive recognition of cyanide ions upon the addition of Hg<SUP>2+</SUP> with a color change back to colorless in the same solution. Finally, <B>SRB</B> was successfully applied with the PEGDMA polymer to sense Hg<SUP>2+</SUP> ions, which was analyzed using fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Design and synthesis of a new squaraine–bis(rhodamine-B) (<B>SRB</B>) chemosensor was in high yield. </LI> <LI> Chemosensor <B>SRB</B> as an ‘off–on’ fluorescent probe for the detection of Hg<SUP>2+</SUP> ion. </LI> <LI> The <B>SRB</B>–Hg<SUP>2+</SUP> complex structure was confirmed via FT-IR studies. </LI> <LI> The reversibility of the <B>SRB</B>–Hg<SUP>2+</SUP> complex was realizable by the introduction of CN<SUP>−</SUP> ion. </LI> <LI> <B>SRB</B> was mixed with PEGDMA polymer for chemosensing the Hg<SUP>2+</SUP> ion. </LI> </UL> </P>

Electrochemical Study for 1,3-Bisdicyanovinylindane

Hyungjoo Kim,Boddu Ananda Rao,Young-A Son 한국염색가공학회 2013 韓國染色加工學會誌 Vol.25 No.2

An ‘OFF–ON’ fluorescent chemosensor based on rhodamine 6G-2-chloronicotinaldehyde for the detection of Al³⁺ ions: Part II

Jeong, Jong Woo,Rao, Boddu Ananda,Lee, Jae-Young,Hwang, Ji-Yong,Son, Young-A Elsevier 2016 Sensors and actuators. B, Chemical Vol.227 No.-

<P><B>Abstract</B></P> <P>A novel, optical rhodamine-2-chloronicotinaldehyde-type chemosensor (<B>R6CN</B>) was designed, synthesized and characterized as a reversible switch. <B>R6CN</B> displayed high selectivity toward Al<SUP>3+</SUP> from various metal ions, including Al<SUP>3+</SUP>, Li<SUP>+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP>, Cs<SUP>+</SUP>, Mg<SUP>2+</SUP>, Ca<SUP>2+</SUP>, Fe<SUP>2+</SUP>, Co<SUP>2+</SUP>, Ni<SUP>2+</SUP>, Cu<SUP>2+</SUP>, Zn<SUP>2+</SUP>, Ag<SUP>+</SUP>, Cd<SUP>2+</SUP>, Hg<SUP>2+</SUP>, Pb<SUP>2+</SUP> and the resultant complex [<B>R6CN</B>-Al<SUP>3+</SUP>]. The ring-opening mechanism of the rhodamine spirolactam was induced by Al<SUP>3+</SUP> binding, and the 1:1 stoichiometric structure between <B>R6CN</B> and Al<SUP>3+</SUP> was adequately supported by the Job-plot evaluation, optical titration, FT-IR and <SUP>1</SUP>H NMR results. Theoretical calculations and modeling simulations were performed using <I>Material Studio 4.3 suite</I> (<I>VAMP</I>), and the results supported the formation of a 1:1 complex between <B>R6CN</B> and Al<SUP>3+</SUP>. The fluorescence quantum yield of <B>R6CN</B>-Al<SUP>3+</SUP> (<I>Φ</I> <SUB>f</SUB> =92.33%) was very high compared to that of the bare ligand. The detection limit for Al<SUP>3+</SUP> was 4.28×10<SUP>−9</SUP> M, and a significant color change from almost colorless to pale-pink occurred in the presence of Al<SUP>3+</SUP>. In turn, the <B>R6CN</B>-Al<SUP>3+</SUP> complex acted as a selective chemosensor toward N<SUB>3</SUB> <SUP>−</SUP> among various anions, including F<SUP>−</SUP>, Cl<SUP>−</SUP>, Br<SUP>−</SUP>, I<SUP>−</SUP>, NO<SUB>3</SUB> <SUP>−</SUP>, CH<SUB>3</SUB>COO<SUP>−</SUP>, ClO<SUB>4</SUB> <SUP>−</SUP>, CN<SUP>−</SUP>, SCN<SUP>−</SUP>, HSO<SUB>4</SUB> <SUP>−</SUP>, HPO<SUB>4</SUB> <SUP>−</SUP> and PF<SUB>6</SUB> <SUP>−</SUP>, in acetonitrile media. Moreover, the <B>R6CN</B>-Al<SUP>3+</SUP> complex also exhibited a high selectivity and sensitivity toward the azide anion upon the addition of Al<SUP>3+</SUP>, and the color reversed back to colorless when the two ions were present together in solution. At last, <B>R6CN</B> was productively applied to the PEGDMA polymer to sense Al<SUP>3+</SUP> ions, which was analyzed using FT-IR, fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel rhodamine-2-chloronicotinaldehyde (<B>R6CN</B>) chemosensor was designed and synthesized in high yield. </LI> <LI> Rhodamine-2-chloronicotinaldehyde (<B>R6CN</B>) exhibits very high selectivity toward Al<SUP>3+</SUP> ions and reversible “turn-off” fluorescence was achieved using the azide (N<SUB>3</SUB> <SUP>−</SUP>) anion. </LI> <LI> The complex between the chemosensor <B>R6CN</B> and Al<SUP>3+</SUP> was found to have a 1:1 ratio by titration. </LI> <LI> The structure of the <B>R6CN</B>-Al<SUP>3+</SUP> complex was determined using <SUP>1</SUP>H NMR and FT-IR titration and molecular modeling studies. </LI> <LI> <B>R6CN</B> was mixed with PEGDMA polymer for chemosensing the Al<SUP>3+</SUP> ion with reversibility by N<SUB>3</SUB> <SUP>−</SUP> ion. </LI> </UL> </P>