Papers by Dr. Boddu Ananda Rao
Russian Journal of General Chemistry, 2018
A series of novel fused bis-aroylbenzodifuran derivatives linked via bis-1,2,3-triazole moiety co... more A series of novel fused bis-aroylbenzodifuran derivatives linked via bis-1,2,3-triazole moiety containing alkane spacers 15, 19a–19d are synthesized in 68–80% yields by the Huisgen cycloaddition (Click) reaction of alkane azides 4–8 with acetylene intermediate 3 followed by cyclization of the corresponding bishydroxyacetophenone derivatives 9–13 with various p-substituted phenacyl bromides 14a–14d. The isolated compounds are characterized by IR, NMR and mass spectral data. The title compounds are screened in vitro for their antimicrobial and antioxidant activities. The results of the studies indicate antimicrobial activity of compounds 16a and 16b compared to that of the standard Streptomycin. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity test of the synthesized compounds indicates the compounds 15d and 16d as highly active as compared to the standard 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT).
Chemistry of Heterocyclic Compounds, 2018
A new series of 4,4'-(3,5-diphenethylbenzo[1,2-b:5,4-b']difuran-2,6-diyl)bis(N-(het)arylthiazol-2... more A new series of 4,4'-(3,5-diphenethylbenzo[1,2-b:5,4-b']difuran-2,6-diyl)bis(N-(het)arylthiazol-2-amine) derivatives have been synthesized from 1,1'-(3,5-diphenethylbenzo[1,2-b:5,4-b']difuran-2,6-diyl)diethanone O,O'-diacetyl dioxime and substituted isothiocyanates under conventional and microwave irradiation conditions. The obtained products were subjected to in vitro antibacterial and antimycobacterial activity tests. Some of the compounds exhibited noteworthy antibacterial activity against Bacillus subtilis (+ve) and Pseudomonas aeruginosa (-ve) strains and antimycobacterial activity against Mycobacterium bovis strain.
Journal of the Chilean Chemical Society , 2018
In the present study a series of novel benzoxazepine (5a-h) derivatives were synthesized by the t... more In the present study a series of novel benzoxazepine (5a-h) derivatives were synthesized by the thermal cyclization reaction of various pyrazole-chalcones (3a-h) with 2-aminophenol, by conventional heating and microwave irradiation (180 W) in solvent-free conditions in short reaction times (9–12 min), giving high yields of products (80–88%). The homogeneity of all the newly synthesized compounds has been checked by TLC. Their IR, NMR, ESI-mass spectral data and elemental analysis are in accord with the assigned structure. The title compounds were evaluated for their antibacterial activity against Gram-positive bacteria Staphylococcus aureus, Bacillus subtilis, and Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli. Compounds 3c, 3h, 5b, 5c, 5g and 5h were found to show good antibacterial activity when compared with that of standard drug Ampicillin. Furthermore, the same library of compounds were evaluated for antifungal activity against Aspergillus nigerzeae, Penicillium italicum and Fusarium oxysporum using Grieseofulvin as standard drug. The results of the above studies show that the compounds 3b, 3c, 3e, 3h, 5a, 5c, 5g and 5h showed good antifungal activity against all the tested organisms.
indian journal of heterocyclic chemistry, 2018
A new series of 6,6'-(4,6-dimethoxy-1,3-phenylene)bis (2- substituted imidazo[2,1-b] [1,3,4]thia... more A new series of 6,6'-(4,6-dimethoxy-1,3-phenylene)bis (2- substituted imidazo[2,1-b] [1,3,4]thiadiazole) derivatives (5a-5h) were synthesized from corresponding 1,1'-(4,6-dimethoxy-1,3-phenylene)bis(2-bromoethanone) and substituted 1,3,4-thiadiazol-2-amine under conventional and microwave irradiation conditions. The structures of all the synthesized compounds were characterized by Fourier transform infrared,¹H nuclear magnetic resonance (NMR),¹³C NMR, mass, and elemental analysis. All products were subjected to in vitro antibacterial and antimycobacterial evaluation. Some of the compounds exhibit good activities against Staphylococcus aureus (+ve), Bacillus subtilis (+ve) strains, and Mycobacterium bovis strain.
Heterocyclic Communications, 2018
New thiazole-substituted dibenzofurans 7a–j were synthesized from dibenzofuran derivatives 5a–b a... more New thiazole-substituted dibenzofurans 7a–j were synthesized from dibenzofuran derivatives 5a–b and substituted thiosemicarbazones 6a–h under conventional and microwave irradiation conditions. The structures of all products were established on the basis of analytical and spectral data. The synthesized compounds were evaluated for their in vitro antibacterial activity against Gram-positive and Gram-negative strains. Compounds 7b, 7d and 7h are active against Bacillus subtilis (+ve), and compound 7i displays good activity against Pseudomonas aeruginosa (-ve) strain. Compounds 7a–j were also evaluated for their in vitro antimycobacterial activity, and compound 7b shows antimycobacterial activity against Mycobacterium bovis strain.
Russian Journal of General Chemistry, 2018
New 4,4'-(4,6-dimethoxy-1,3-phenylene)bis{2-[2-(substituted benzylidene)hydrazinyl]thiazole} deri... more New 4,4'-(4,6-dimethoxy-1,3-phenylene)bis{2-[2-(substituted benzylidene)hydrazinyl]thiazole} derivatives (5a–5j) have been synthesized from the corresponding 1,1'-(4,6-dimethoxy-1,3-phenylene)bis(2,2- dibromoethanone) and substituted thiosemicarbazones by the conventional method and under microwave irradiation. Structures of the synthesized compounds were characterized by FT-IR, 1H, and 13C NMR and Mass spectra. The products were evaluated for their in vitro antibacterial activity against Gram-positive and Gramnegative stains. Some of the compounds 5b, 5f, 5h demonstrated high activity against B. subtilis (+ve), compound 5c exhibited high activity against E. coli (–ve) and P. aeruginosa (–ve) stains. Among the titled compounds also evaluated for their in vitro antimycobacterial activity, the product 5b demonstrated pronounced antimycobacterial activity against M. bovis stain.
Russian Journal of General Chemistry, 2018
A series of (Z)-3-{[3-oxobenzofuran-2(3H)-ylidene]methyl}-4H-chromen-4-one derivatives have been ... more A series of (Z)-3-{[3-oxobenzofuran-2(3H)-ylidene]methyl}-4H-chromen-4-one derivatives have been synthesized from 2-hydroxyl acetophenones by the Vilesmeier–Haack reaction, Claisen–Schmidt reaction and mercury(II) acetate/cupric bromide. All the synthesized compounds were characterized by IR, 1H and 13C NMR, and mass spectral data and elemental analysis. The products were tested for their in vitro antimicrobial activity.
Russian Journal of General Chemistry, 2017
In the present study, a series of novel 1,2,3-triazoles derivatives (4a–4c) were synthesized by t... more In the present study, a series of novel 1,2,3-triazoles derivatives (4a–4c) were synthesized by the 1,3-dipolar cycloaddition (click-reaction) of 1-phenyl-3-[2-(prop-2-yn-1-yloxy)phenyl substituted]-1H-pyrazole-4-carbaldehyade (3a–3c) with various aryl azides in the presence of sodium ascorbate and copper sulphate with high yields. The required precursors 3a–3c were synthesized by the reaction of 1-(2-hydroxy phenyl substituted)ethanones (1a–1c) with propargyl bromide via 1-[2-(prop-2-yn-1-yloxy)phenyl substituted] ethanone (2a–2c), followed by reaction with phenyl hydrazine. The newly synthesized 1,2,3-triazole-pyrazole derivatives were characterized by analytical and spectral data. All synthesized compounds were evaluated in vitro for their antibacterial and antifungal activity. The most active compounds 4a 5 –4a 7 demonstrated a broad spectrum of antibacterial activity against all strains used for testing. Compounds (4a 4 , 4b 1 , 4c 1 , 4c 2 ) demonstrated significant antifungal activity at the concentration of 10 μg/mL.
Heterocyclic Communications, 2017
New 4,4′-(4,6-dimethoxy-1,3-phenylene)-bis(N-substituted thiazol-2-amine) derivatives 5a–j were s... more New 4,4′-(4,6-dimethoxy-1,3-phenylene)-bis(N-substituted thiazol-2-amine) derivatives 5a–j were synthesized from 1,1′-(4,6-dimethoxy-1,3-phenylene)-bis(2-bromoethanone) 3 and substituted thioureas 4a–j under conventional and microwave irradiation conditions. All products were subjected to in vitro antibacterial and anti-TB evaluation. Some of the compounds exhibit good activities against Bacillus subtilis (+ve), Escherichia coli (−ve) strains and Mycobacterium tuberculosis H37Rv.
Russian Journal of General Chemistry, 2017
Vanillin, hydrazone and 1,2,3-triazole containing functional groups derivatives demonstrate antib... more Vanillin, hydrazone and 1,2,3-triazole containing functional groups derivatives demonstrate antibacterial activity. In the present work, we present synthesis of eight new vanillin related hydrazone derivatives bearing 1,2,3-triazole ring skeleton 9a–9e, 10a–10e obtained with high yields by the coupling of aldehydes 6 and 7 with substituted benzohydrazides 8a–8e in ethanol. IR, NMR and MS data and elemental analysis confirm the structures of products. All title compounds were evaluated in vitro for their antibacterial activity against a panel of Gram positive and Gram negative bacteria and compounds 9d and 10d exhibited high activity.
Chemistry of Heterocyclic Compounds, 2017
A novel series of spiro[chromene-2,1'-cyclohexan]-4(3H)-one derivatives containing either a chalc... more A novel series of spiro[chromene-2,1'-cyclohexan]-4(3H)-one derivatives containing either a chalcone or flavanone fragment in their molecules was synthesized. 2'-Hydroxychalcones, containing a spirochromanone moiety, underwent cyclocondensation with formation of a condensed pyran ring. The catalytic efficiency of TFA in the chalcone–flavanone transformation has been demonstrated. The structures of the compounds have been established on the basis of elemental analysis and standard spectroscopic data. The synthesized compounds were tested for their antibacterial and antifungal activities.
Journal of the Serbian Chemical Society , 2017
A series of novel bis(1,2,3-triazoles) derivatives 7a–m were synthesized by the 1,3-dipolar cycl... more A series of novel bis(1,2,3-triazoles) derivatives 7a–m were synthesized by the 1,3-dipolar cycloaddition (click-reaction) of 1-methyl-3,5-bis(2-(prop-2-yn-1-yloxy)phenyl)-4,5-dihydro-1H-pyrazole (5) with various aralkyl azides 6a–m in the presence of sodium ascorbate and copper sulphate with good yields. The required precursor 5 was synthesized by reacting (E)-1,3-bis(2-hydroxyphenyl)prop-2-en-1-one (3) with methylhydrazine hydrate via 2,2′-(1-methyl-4,5-dihydro-1H-pyrazole-3,5-diyl)diphenol 4, followed by reaction with propargyl bromide. The homogeneity of all the newly synthesized compounds was checked by TLC. The IR, NMR, mass spectral data and elemental analysis were in accord with the assigned structure. The title compounds were evaluated for their antibacterial activity against various bacterial strains, i.e., Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis; compounds 7f–7h and 7j were found to be moderately active against the bacteria, when compared with that of the standard drug. Furthermore, the same library of compounds was evaluated for their antioxidant activity using the nitric oxide radical scavenging activity. The results of the study showed that compounds 7e–7h and 7k–7m showed good radical scavenging activity.
Background: Over a decade, a number of papers have been published on the usage of ionic liquids (... more Background: Over a decade, a number of papers have been published on the usage of ionic liquids (ILs) and Microwave-Assisted Organic Synthesis (MAOS), which displayed their benefits with respect to the conventional synthetic procedures, for current generation of fast, efficient and environmental friendly synthetic methodologies. The aim of the present study is the synthesis of linear and angular spirochromanone derivatives using microwave irradiation with the IL. As the microwave assisted organic synthesis (MAOS) with IL as a solvent is environmental friendly and non-volatile, therefore it allows simple separation and catalyst recycling.
A novel, optical rhodamine-2-chloronicotinaldehyde-type chemosensor (R6CN) was designed, synthesi... more A novel, optical rhodamine-2-chloronicotinaldehyde-type chemosensor (R6CN) was designed, synthesized and characterized as a reversible switch. R6CN displayed high selectivity toward Al 3+ from various metal ions, including Al 3+ , Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , Hg 2+ , Pb 2+ and the resultant complex [R6CN-Al 3+ ]. The ring-opening mechanism of the rhodamine spirolactam was induced by Al 3+ binding, and the 1:1 stoichiometric structure between R6CN and Al 3+ was adequately supported by the Job-plot evaluation, optical titration, FT-IR and 1 H NMR results. Theoretical calculations and modeling simulations were performed using Material Studio 4.3 suite (VAMP), and the results supported the formation of a 1:1 complex between R6CN and Al 3+. The fluorescence quantum yield of R6CN-Al 3+ (˚ f = 92.33%) was very high compared to that of the bare ligand. The detection limit for Al 3+ was 4.28 × 10 −9 M, and a significant color change from almost colorless to pale-pink occurred in the presence of Al 3+. In turn, the R6CN-Al 3+ complex acted as a selective chemosensor toward N 3 − among various anions, including F − , Cl − , Br − , I − , NO 3 − , CH 3 COO − , ClO 4 − , CN − , SCN − , HSO 4 − , HPO 4 − and PF 6 − , in acetonitrile media. Moreover, the R6CN-Al 3+ complex also exhibited a high selectivity and sensitivity toward the azide anion upon the addition of Al 3+ , and the color reversed back to colorless when the two ions were present together in solution. At last, R6CN was productively applied to the PEGDMA polymer to sense Al 3+ ions, which was analyzed using FT-IR, fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.
A novel ethylenediamine derivative of a rhodamine 6G silica particle (RSSP) was covalently grafte... more A novel ethylenediamine derivative of a rhodamine 6G silica particle (RSSP) was covalently grafted ontothe surface of mesoporous silica to create a fluorescent chemosensing hybrid material for the detection ofFe3+. The prepared RSSP was dispersed in water, and its optical sensing response to various metal cations(Ag+, Na+, Li+, K+, Cs+, Hg2+, Cu2+, Ca2+, Cd2+, Co2+, Fe2+, Mg2+, Ni2+, Pb2+, Zn2+, Fe3+and Al3+) was evaluatedthrough the resulting fluorescence spectra. Upon coordination with Fe3+, the promoted ring openingof the rhodamine spirolactam ring in the RSSP activated a fluorescence response via CHEF (chelationenhancement fluorescence). This fluorescence enhancement was induced by the spirolactam ring systemof the chemosensor immobilized in the pore. Conversely, the fluorescence response of the RSSP–Fe3+complex was quenched by the addition of EDTA, which abstracted the Fe3+ion from the complex andturned the sensor off, confirming that the recognition process was reversible. The proposed chemosensoralso exhibited excellent selectivity for Fe3+over competing environmentally relevant metal ions. Thechemosensor can also be used over a wide pH range and was readily regenerated. The sensing ability ofRSSP makes it desirable for practical applications in microfluidics analysis tools, intracellular bio-imagingand lab-on-a-chip development.
A rhodamine 6G-based probe bearing a carbazole unit (R6G-CB) was developed as a fluorescent chela... more A rhodamine 6G-based probe bearing a carbazole unit (R6G-CB) was developed as a fluorescent chelation agent for Cu2+ and a chemodosimeter for Ce4+ in acetonitrile:aqueous (5:5, v/v) media. The R6G-CB chemosensor exhibited selectivity toward Cu2+ ions over other metal cations by showing “off-on”-type changes in its absorption and emission spectra, which were attributed to the transformation of the non-fluorescent and colorless spirolactam derivative to the ring-opened, fluorescent, pink amide. The Cu2+-induced chelation-enhanced fluorescence (CHEF) is associated with the spirolactam ring opening of the rhodamine unit. This R6G-CB chemosensor also showed a fast response (<1 min) to an irreversible Ce4+-promoted oxidation reaction, responding instantaneously at room temperature with a change that is observable by the naked eye. This through-bond energy transfer (TBET)-based sensor is also highly selective and sensitive to Ce4+. Spectroscopic analysis revealed that different structural substitution patterns of the probe resulted in different sensitivities and selectivities for specific metal ions. The optical titration, Job's plot estimation, mass spectroscopy, and Fourier transform infrared (FT-IR) results indicated that 1:2 and 1:1 complexes formed between R6G-CB and Cu2+ and between R6G-CB and Ce4+, respectively. The reversibility of the R6G-CB chemosensor was verified via its spectral response to Cu2+ and EDTA disodium salt titration experiments. All of these features make these sensors advantageous for Cu2+/Ce4+ test strip applications. Due to the significant absorption intensity changes resulting from the addition of Cu2+ and Ce4+ ions, the novel system can act as a single-output combinational logic circuit with two chemical inputs. Finally, density functional theory (DFT) calculations were performed to gain insight into the structures and electronic properties of R6G-CB, R6G-CB-Cu2+ complexes and R6G-CB-Ce4+ adducts.
A new rhodamine-6G phenylthiourea derivative (L1) condensed product was developed as a fluores-ce... more A new rhodamine-6G phenylthiourea derivative (L1) condensed product was developed as a fluores-cent and colorimetric dual chemosensor in acetonitrile with more selective towards Hg2+and F−ions.Hg2+-promoted spirolactam ring opening of the rhodamine moiety induced urea formation through thediphenylcarbodiimide intermediate from the thiourea moiety. It demonstrates high selectivity for sensingHg2+with about 700-fold enhancement in fluorescence emission intensity and micromolar sensitivity(limit of detection 4.52 × 10−7M) in comparison with other various metal ions. Hg2+ions coordinatedreversibly to L1, forming a 1:2 metal–ligand complex. The thiourea moiety provided an anion bindingsite, and the rhodamine system was responsible for fluorescence. In turn, the chemosensor L1 acted asa selective chemosensor toward F−among various anions. Thus, L1 associated with F−with 1:1 stoi-chiometry. A recognition mechanism based on the binding modes of Hg2+and F−ions were proved bythe analytical techniques like UV–vis, changes in fluorescence,1H NMR, FT-IR, ESI-mass and HRMS. Inaddition, this chemosensor exhibited highly selective and sensitive recognition of azide (N3−) anionsupon the addition of Hg2+with a color change back to colorless in the same solution.
We report the design and synthesis of a novel chemosensor (RGPS) rhodamine-based indicator for se... more We report the design and synthesis of a novel chemosensor (RGPS) rhodamine-based indicator for selective
detection of Cu2+ ion. Sensing behavior toward various metal ions (M=Hg2+, Cu2+, Co2+, K+, Cs+, Ag+, Pb2+, Zn2+, Mg2+, Fe3+,
Ni2+, Li+ and Al3+) was investigated by UV-Vis and fluorescence spectroscopy in acetonitrile:water (CH3CN-H2O, v/v, 9:1)
solution. The indicator exhibited highly selective and sensitive colorimetric and ‘‘turn-on’’ fluorescent responses toward Cu2+
ions based on the ring-opening mechanism of the rhodamine spirolactam in an CH3CN-H2O (v/v, 9:1) solution. The obvious
change from colorless to pale pink upon the addition of Cu2+ could make it a suitable “naked eye” indicator for Cu2+. More
significantly, the sensor displayed a remarkable colorless to yellowish green fluorescence switch in the presence of Cu2+ ions.
The limit of detection is proved 1.405×10-7 M from titration and 1:1 binding ratio is proved from jobs plot method. Finally,
we proposed a reversible ring-opening mechanism (OFF-ON) of the rhodamine spirolactam induced by Cu2+ binding and
forming a 1:1 stoichiometric complex of RGPS-Cu2+ which is supported by the material studio theory calculations.
This paper describes the optimized design, synthesis and application of three novel thiosemicarba... more This paper describes the optimized design, synthesis and application of three novel thiosemicarbazide-appended rhodamine spirolactam derivatives as ‘turn-on’ colorimetric and fluorescent chemodosimeters(1–3) for the detection of Hg2+in aqueous samples with a broad pH range (5.0–9.4). The ‘turn-on’ change inthe color and fluorescence signals of 1–3 is based on a Hg2+-triggered reaction that converts the thiosemi-carbazide form to the 1,3,4-oxadiazole form. The results of13C NMR studies indicated that the basicityof the ‘C S’ can be varied from ı 183.05 (for nitro) to 181.3 ppm (for methyl) by changing the R group inthe chemodosimeter. Electronic and spectrofluorimetric studies indicated that the order of the bindingconstants of these chemodosimeters with Hg2+ions is 1 > 2 > 3, which may be dependent on the sub-stituent. Chemodosimeters 1–3 exhibit a stable response to Hg2+from 2.5 × 10−7to 2.0 × 10−5M witha detection limit of 10−8M. The response of these chemodosimeters to Hg2+is highly selective and pHinsensitive, and the response time is rapid. All of these unique features make these sensors particu-larly favorable for Hg2+test strip applications. These sensors have been preliminarily used for the highlysensitive monitoring of Hg2+levels in aqueous media with satisfactory resolution.
Herein, we report an effective strategy based on coordination-induced signaling by introducing a ... more 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 (SRB) as an ‘off–on’ fluorescent probe for the detection of Hg2+ ions were investigated. SRB exhibited high selectivity toward Hg2+ in the presence of various metal ions, such as Al3+, Ag+, Co2+, Cs+, Cu2+, Fe3+, K+, Li+, Mg2+, Na+, Ni2+, Pb2+, and Zn2+, and the resulting complex [SRB–Hg2+] was investigated using UV–vis and fluorescence spectroscopy in acetonitrile (CH3CN). The ‘off–on’ fluorescence and color signal change of the probe are based on a Hg2+-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 Hg2+ binding and the 1:1 stoichiometric structure of SRB and Hg2+ were confirmed using a Job's plot estimation, optical titration and FT-IR. Subsequently, a SRB–Hg2+ complex chemosensor was employed to detect CN− in the presence of different anions, such as Br−, CH3COO− or AcO−, Cl−, ClO4−, F−, HPO4−, HSO4−, I−, N3−, NO3−, PF6− and SCN−, in acetonitrile. In addition, this sensor exhibited highly selective and sensitive recognition of cyanide ions upon the addition of Hg2+ with a color change back to colorless in the same solution. Finally, SRB was successfully applied with the PEGDMA polymer to sense Hg2+ ions, which was analyzed using fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.
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Papers by Dr. Boddu Ananda Rao
detection of Cu2+ ion. Sensing behavior toward various metal ions (M=Hg2+, Cu2+, Co2+, K+, Cs+, Ag+, Pb2+, Zn2+, Mg2+, Fe3+,
Ni2+, Li+ and Al3+) was investigated by UV-Vis and fluorescence spectroscopy in acetonitrile:water (CH3CN-H2O, v/v, 9:1)
solution. The indicator exhibited highly selective and sensitive colorimetric and ‘‘turn-on’’ fluorescent responses toward Cu2+
ions based on the ring-opening mechanism of the rhodamine spirolactam in an CH3CN-H2O (v/v, 9:1) solution. The obvious
change from colorless to pale pink upon the addition of Cu2+ could make it a suitable “naked eye” indicator for Cu2+. More
significantly, the sensor displayed a remarkable colorless to yellowish green fluorescence switch in the presence of Cu2+ ions.
The limit of detection is proved 1.405×10-7 M from titration and 1:1 binding ratio is proved from jobs plot method. Finally,
we proposed a reversible ring-opening mechanism (OFF-ON) of the rhodamine spirolactam induced by Cu2+ binding and
forming a 1:1 stoichiometric complex of RGPS-Cu2+ which is supported by the material studio theory calculations.
detection of Cu2+ ion. Sensing behavior toward various metal ions (M=Hg2+, Cu2+, Co2+, K+, Cs+, Ag+, Pb2+, Zn2+, Mg2+, Fe3+,
Ni2+, Li+ and Al3+) was investigated by UV-Vis and fluorescence spectroscopy in acetonitrile:water (CH3CN-H2O, v/v, 9:1)
solution. The indicator exhibited highly selective and sensitive colorimetric and ‘‘turn-on’’ fluorescent responses toward Cu2+
ions based on the ring-opening mechanism of the rhodamine spirolactam in an CH3CN-H2O (v/v, 9:1) solution. The obvious
change from colorless to pale pink upon the addition of Cu2+ could make it a suitable “naked eye” indicator for Cu2+. More
significantly, the sensor displayed a remarkable colorless to yellowish green fluorescence switch in the presence of Cu2+ ions.
The limit of detection is proved 1.405×10-7 M from titration and 1:1 binding ratio is proved from jobs plot method. Finally,
we proposed a reversible ring-opening mechanism (OFF-ON) of the rhodamine spirolactam induced by Cu2+ binding and
forming a 1:1 stoichiometric complex of RGPS-Cu2+ which is supported by the material studio theory calculations.