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Öğe Calix[4]arene based a NIR-fluorescent sensor with an enhanced stokes shift for the real-time visualization of Zn(II) in living cells(ELSEVIER SCIENCE SA, 2020) Erdemir, Serkan.; Malkondu, Sait.Zinc(II) plays key roles actively involved in fundamental biological functions in the body. However, zinc dysmetabolism results in a number of human diseases. Therefore, miscellaneous techniques are needed to understand the complete biological role of Zn(II) in tissues and cells. Here, we introduce a novel calix[4]arene derivative (CIP), appended with two isophorone units via a 4-bromophenol linker for the fluorescence sensing Zn (II). CIP showed high fluorogenic selectivity for Zn(II) over a wide range of biologically and environmentally relevant metal ions in DMSO/H2O (v/v, 8/2, PBS buffer, 0.5 mM, pH 7.4) and has superior sensitivity of (6.75 nM) for Zn(II). Free CIP has very low emission but demonstrated the distinct "turn-on" emission enhancement response toward Zn(II) at near infrared region. CIP allowed the fabrication of a rapid and convenient TLC strip sensor for Zn(II)-selective detection. Moreover, this is the first report on a calix[4]are derivative used as a NIR fluorescence probe that monitors changes in intracellular Zn(II) levels and can penetrate into living cells.Öğe A colorimetric and fluorometric probe for hydrazine through subsequent ring-opening and closing reactions: Its environmental applications(ELSEVIER, 2020) Erdemir, Serkan.; Malkondu, Sait.Hydrazine (N2H4), as one of the essential industrial chemicals, is main water contaminant and highly toxic for human health. Therefore, the rapid, selective and sensitive detection strategies for hydrazine are needed. The present study describes the first example of a receptor based on pyrazolone and hydrazide formation by subsequent ring-opening and closing reactions displayed distinct naked eye colorimetric and visual fluorescence sensing towards hydrazine with rapid reactivity and very good selectivity over various anions, cations and amines. The probe BC was obtained in good yield by three stages. The sensing mechanism was confirmed by H-1 NMR and C-13 NMR spectra. Upon interaction with hydrazine, coumarin ring was easily opened and pink color followed by purple was formed. The more hydrazine addition triggered pyrazolone ring formation with yellow colored solution in company with the remarkable cyan blue turn-on fluorescence output. An easy-to-produce TLC test strip enables to determine hydrazine in the solution. The results were successfully shown to be convenient and efficient for hydrazine detection. Therefore, the present strategy is supposed to be widely applied to fabricate fluorescent sensors for detection of hydrazine.Öğe Dual-emissive fluorescent probe based on phenolphthalein appended diaminomaleonitrile for Al3+ and the colorimetric recognition of Cu2+(ELSEVIER SCI LTD, 2019) Erdemir, Serkan.; Malkondu, Sait.A novel dual emissive fluorescent probe was designed and synthesized by linking phenolphthalein and diaminomaleonitrile units. The present probe (PDM) can be used not only for fluorogenic detection of Al3+ by way of the excited enol-keto forms but also colorimetric detection of Cu2+. PDM probe showed a selective fluorescence enhancement with dual channel emissions for Al3+ in a mixture of EtOH/H2O (9/1). H-1 NMR and DFT methods were also carried out to support the complexation between PDM and Al3+ ion. In addition, PDM presented highly selective colorimetric response for Cu2+ over other metal ions. The reversibility of PDM-Al3+ and PDM-Cu2+ complexes was successively established with the addition of TBAF and EDTA, respectively. The detection limits were determined to be 92.0 nM for Al3+ and 2.81 mu M for Cu2+. The obtained results revealed that the designed PDM probe could be suitable for monitoring Al3+ under UV lamp and Cu2+ in water samples with the naked eye, which was rapid, convenient, low-cost and environmental friendly.Öğe Fluorometric dual sensing of Hg2+ and Al3+ by novel triphenylamine appended rhodamine derivative in aqueous media(ELSEVIER SCIENCE SA, 2019) Erdemir, Serkan.Triphenylamine appended rhodamine (named probe TR) was built as a selective fluorescent probe for Al3+ and Hg2+ ions through different sensing mechanisms. TR demonstrated a distinct fluorescence enhancing at 501 and 580 nm towards Al3+ and Hg2+ ions due to the "PET-off" (Photoinduced electron transfer-off) and "FRET-on" (Fluorescence resonance energy transfer-on) processes, respectively. The binding modes between TR with Al3+ and Hg2+ were found to be 1:1 by job plot analysis. The limits of detection of TR for sensing Al3+ and Hg2+ are down to 71.8 nM and 0.48 mu M, respectively. At the same time, the complexation details between the probe TR with Al3+ and Hg2+ ions were investigated by FTIR, (HNMR)-H-1 experiments and DFT calculations. Moreover, simple test papers coated probe TR were successively developed for the rapid monitoring of Al3+ and Hg2+ ions.Öğe On-site and low-cost detection of cyanide by simple colorimetric and fluorogenic sensors: Smartphone and test strip applications(ELSEVIER, 2020) Erdemir, Serkan.; Malkondu, Sait.Cyanide is potentially hazardous and quickly acting chemical used in many fields of industry. Therefore, detection of cyanide is of main health concern due to its serious impacts on living organisms. In this context, we have developed rapid, low-cost and on-site sensory two molecules for the colorimetric and fluorogenic sensing of cyanide ion in aqueous samples and food samples. The prepared probes undergo distinct visual color change and exhibits selective fluorogenic turn-on or turn-off response towards cyanide. Competing anions have little or negligible effect on the detection of cyanide. The limit of detection for cyanide ion was calculated as low as 0.45 mu M. Free receptors could be successfully regenerated by treating them with Ag+ ion. Moreover, a new visual colorimetric strip based on paper was fabricated with the pale yellow-to-pink color change signal. The fabricated test strips also demonstrated excellent selectivity towards cyanide ion without interfering possible fluoride and acetate ions. The smartphone-based technique which could directly read out the color value using a smartphone revealed an excellent potential for the cyanide detection without additional device.Öğe Phenanthroimidazole and dicyanovinyl-substituted triphenylamine for the selective detection of CN-: DFT calculations and practically applications(ELSEVIER SCIENCE SA, 2020) Ozdemir, Ahmet.; Erdemir, Serkan.A novel CN- selective fluorescent turn-on sensor (TPMN) possessing triphenylamine and phenanthroimidazole as signaling units and dicyanovinyl unit for the binding site was designed and synthesized. TPMN exhibited a drastic change in its emission spectra with about 13-fold fluorescence enhancement when treated with CN-, while other tested anions could not arouse the fluorescence enhancement. The experimental and theoretical calculation results showed that this increase in fluorescence intensity of TPMN in presence of CN- is due to the large decrease in the ICT effect by the addition of CN- ion to beta-carbon of the dicyanovinyl moiety. TPMN could selectively detect CN- with a detection limit of 0.23 mu M among the common anions. The CN--binding mode was well-characterized to be 1:1 by using Job's plot with an association constant of 5.36 (logK(a)). Besides, the possible utilization of TPMN was successively tested in water samples and test kits.Öğe QCM sensors coated with calix[4]arenes bearing sensitive chiral moieties for chiral discrimination of 1-phenylethylamine enantiomers(SPRINGER, 2019) Ozcelik, Egemen.; Temel, Farabi.; Erdemir, Serkan.; Tabakci, Begum.; Tabakci, Mustafa.This article describes the enantiomeric discrimination properties of new chiral calix[4]arene derivatives bearing (S)-/(R)-1-phenylethylamine moieties (5a and 5b, respectively) towards the 1-phenylethylamine enantiomers on QCM surface. Initial experiments demonstrated that the 5b coated QCM sensor was the most effective sensing material for enantiomeric discrimination of (R)-/(S)-1-phenylethylamine by exhibiting much more sensing ability towards (R)-enantiomer than (S)-enantiomer. Sensitivity, detection limit and time constant of the 5b coated QCM sensor has been were calculated as 0.082 Hz/mu M, 2.7 mu M, and 319.2 s, respectively. Additionally, effects of calixarene content and different coating technique on enantiomeric discrimination, and Langmuir and Freundlich isotherms of the sensing results also were studied. As a result, it has been demonstrated that the coating of QCM sensor with a chiral calix[4]arene (5b) having (S)-1-phenylethylamine moieties provides substantially enantiomeric discrimination of 1-phenylethylamine enantiomers.Öğe Red and blue emitting fluorescent probe for cyanide and hypochlorite ions: Biological sensing and environmental analysis(ELSEVIER SCI LTD, 2020) Malkondu, Sait.; Erdemir, Serkan.; Karakurt, Serdar.Excessive levels of hypochlorite and cyanide ions are considered as the major threats towards human health and environment. Therefore, many researchers make considerable effort to develop small molecules for the quick, accurate and easy detection of biologically and environmentally important anions. Moreover, design of multiple analyte sensing sensors is still challenging issue due to broad application area. In the present study, we introduce a novel chemosensor (P) based on benzothiazole and diaminomaleonitrile units for the detection hypochlorite and cyanide ions in biological and environmental samples. The detection ability of P was examined towards a pool of analyte containing anions, cations and reactive oxygen species. P undergoes sharp turn-on fluorescence enhancement induced by hypochlorite or cyanide over other anions. The fluorescence response is attributed to oxidation of imine bond by hypochlorite or deprotonation of -NH2 and -OH functions by cyanide. The selectivity and sensitivity data demonstrated by P over other anions renders it an excellent candidate for hypochlorite and cyanide detection in biological and aqueous environments. Moreover, this is the first study that single probe has an ability of detecting both hypochlorite and cyanide anions through two distinct sensing modes.Öğe A reversible calix[4]arene armed phenolphthalein based fluorescent probe for the detection of Zn2+ and an application in living cells(WILEY, 2019) Erdemir, Serkan.; Malkondu, Sait.; Kocyigit, Ozcan.A reversible and easy assembled fluorescent sensor based on calix[4]arene and phenolphthalein (C4P) was developed for selective zinc ion (Zn2+) sensing in aqueous samples. The probe C4P demonstrated high selective and sensitive detection towards Zn2+ over other competitive metal ions. Interaction of Zn2+ with a solution of C4P resulted in a considerable increment in emission intensity at 440 nm (lambda(ex) = 365 nm) due to the suppression of photoinduced electron transfer (PET) process and the restriction of C=N isomerization. The binding constant (K-a) of C4P with Zn2+ was calculated to be 4.50 x 10(11) M-2 and also the limit of detection of C4P for Zn2+ was as low as 0.108 mu M (at 10(-7) M level). Moreover, the fluorescence imaging in the human colon cancer cells suggested that C4P had great potential to be used to examine Zn2+ in vivo.
