Dual fluorescence response of calix[4]arene-1,8-naphthalimide derivatives towards Hg(II) /Cr(VI) and their antimicrobial studies of transparent biofilms with hyaluronic acid.

In this study, 4-sulfo-1,8-naphthalimide calixarene of derivatives were prepared (3 and 4) then transparent biofilms of the Ag salts of these compounds were formed in the presence of hyaluronic acid (HA), and antimicrobial properties were investigated. In chemosensor studies, the sensing ability behavior of 3 and 4 towards some cations and anions was investigated by fluorescence spectroscopy. It was observed that the prepared chemosensors show selectivity towards Hg(II) and Cr(VI). Ligand-ion interaction occurs according to the photo-induced electron transfer (PET) mechanism. The stoichiometric ratio was calculated by using Stern-Volmer plot method and binding constant Ksv values were found as 5.2 × 107 M-1 and 5.5 × 107 M-1 for 3-Hg(II) and 4-Hg(II) complexes, respectively and 4.0 × 107 M-1 and 4.3 × 107 M-1 for 3-Cr(VI) and 4-Cr(VI) complexes. The detection limits of the complexes of 3-Hg(II) and 4-Hg(II) are 6.35 × 10-12and 6.81 × 10-12, while those of 3-Cr(VI) and 4-Cr(VI) are 1.41 × 10- 11and 8.37 × 10-12, respectively. As a result of the antimicrobial test performed with these compounds, it was observed that the most effective material was HA-3Ag, which showed a significant antibacterial effect against Sarcina lutea (S. lutea) at a minimum inhibitory concentration (MIC) value of 0.097 mg/mL.

A New Benzothiazin-functionalized Calix[4]arene-based Fluorescent Chemosensor for the Selective Detection of Co2+ Ion.

Calixarenes, which have a great place in supramolecular chemistry, have become the most prominent macrocyclic compounds in synthetic organic chemistry due to their easy synthesis and functionalization. In this study, p-tert-butyl calix[4]arene dihydrazide derivative was synthesized and then reacted with 3-oxo-3,4-dihydro-2 H-benzo[b][1,4] thiazin-2-ylideneacetyl chloride to prepare new calixarene based chromophore compound 4. The structure of the synthesized compound was elucidated by spectroscopic methods such as 1H NMR 13C NMR and FT-IR spectroscopy. Chromogenic and fluorescence properties of compound 4 were evaluated. It was observed from both studies that compound 4 was Co2+ selective and shows fluorescence Switched-off behavior. Stoichiometry, binding constant and the detection limit were calculated. The stoichiometry between compound 4 and Co2+ was found to be 1:1. The binding constant value (K) was calculated as 666.67 M- 1 using Benesi-Hildebrand equation, while the detection limit for Co2+ ion was calculated as 0.0465 µM.

Formation of the inclusion complex of water soluble fluorescent calix[4]arene and naringenin: solubility, cytotoxic effect and molecular modeling studies.

Naringenin is considered as an important flavonoid in phytochemistry because of its important effect on cancer chemoprevention. Unfortunately its poor solubility has restricted its therapeutic applications. In this study, an efficient water-soluble fluorescent calix[4]arene (compound 5) was synthesized as host macromolecule to increase solubility and cytotoxicity in cancer cells of water-insoluble naringenin as well as to clarify localization of naringenin into the cells. Complex formed by host-guest interaction between compound 5 and naringenin was analyzed with UV-visible, fluorescence, FTIR spectroscopic techniques and molecular modeling studies. Stern-Volmer analysis showed binding constant value of Ksv 3.5 × 107 M-1 suggesting strong interaction between host and guest. Binding capacity shows 77% of naringenin was loaded on compound 5. Anticarcinogenic effects of naringenin complex were evaluated on human colorectal carcinoma cells (DLD-1) and it was found that 5-naringenin complex inhibits proliferation of DLD-1 cells 3.4-fold more compared to free naringenin. Fluorescence imaging studies show 5-naringenin complex was accumulated into the cytoplasm instead of the nucleus. Increased solubility and cytotoxicity of naringenin with fluorescent calix[4]arene makes it one of the potential candidates as a therapeutic enhancer. For deep understanding of host-guest interaction mechanisms, complementary multiscale molecular modeling studies were also carried out.Communicated by Ramaswamy H. Sarma.

Enantioselective resolution of racemic flurbiprofen methyl ester by lipase encapsulated mercapto calix[4]arenes capped Fe3O4 nanoparticles.

This work presents the synthesis of new mercapto calix[4]arenes derivatives (4 and 5). These derivatives were capped on Fe3O4 magnetic nanoparticles and subsequently encapsulated with Candida rugosa through sol-gel method to furnish enc-4 and enc-5, respectively, to enhance catalytic activity and enantioselectivity of lipase for hydrolysis reaction of racemic flurbiprofen methyl ester. Catalytic activity and enantioselectivity of enc-4 and enc-5 were assayed at different pH and temperature conditions and it was found that the resultant encapsulated enzyme exhibited higher thermal and operational stabilities compared to the free lipase in which enc-5 showed the excellent rate of enantioselectivity (E = 176) for S-flurbiprofen better than free lipase (E = 137) at pH 7 and 35 °C for 48 h. The time study shows that enantioselectivity reached the maximum value of E = 244 after 72 h. Catalytic activity  of these materials was hardly affected by 20 and 23% after five usages of enc-4 and enc-5, respectively.

New water soluble Hg2+ selective fluorescent calix[4]arenes: Synthesis and application in living cells imaging.

The present study demonstrates the synthesis of water-soluble fluorescent calix[4]arenes (6 and 7) and its application in living cell imaging for Hg2+ detection at a low level. The synthesized fluorescent ligands 6 and 7 were characterized by 1H NMR technique. The fluorescent study showed both water soluble ligands were Hg2+ selective and follow photo-induced electron transfer (PET) process. From the fluorimeter titration experiment detection limit was calculated as 1.14×10-5 and 3.42×10-5 for ligand 6 and 7, respectively. From the Benesi-Hildebrand plot binding constant values were evaluated as 666.7 and 733.3M-1 for 6 and 7, respectively. The interactions between ligands 6 and 7 and Hg2+ were also demonstrated in living cells, SW-620, using Fluorescent Cell Imager. While ligands 6 and 7 alone show fluorescent properties, they loss their action with the presence of Hg2+ in SW-620 cells.

Dual Fluorescence Response of Newly Synthesized Naphthalene Appended Calix[4]arene Derivative towards Cu2+ and I.

In the present work new naphthalene appended calix[4]arene (NAC4) i.e. 5,11,17,23-tetra-tert-butyl-25,27-di((2-amido(1-naphthlene)ethyl)-26,28-dihydroxy calix[4]arene (6) was designed and successfully synthesized. NAC4 was characterized by 1HNMR and FTIR. To explore the complexation behavior and fluorescence response of NAC4, UV-visible and fluorescence studies were carried out with series of metal ions and anions that include solvatochromic effect, ion-ligand response and interference on absorption and fluorescence spectra. Results show that the NAC4 is highly Cu2+ and I-selective. The ligand ion interaction follow photoinduced electron transfer (PET) mechanism. The stiochiomatric ratio of ion-ligand was calculated as 1:1 by using Job's plot method and binding constant Ka values were calculated by using Benesi-Hildebrand equation as 1×103 and 8×102 M-1 with detection limit of 1.05×10-5 and 4.0×10-5 M for Cu2+ and I- respectively. Graphical Abstract ᅟ.

A New Piperidine Derivatized-Schiff Base Based "Turn-on" Cu2+Chemo-Sensor.

In this study, we report the synthesis of new Schiff base E-1-(((1-benzylpiperidin-4-yl)imino)methyl)naphthalenee-2-ol (L) and evaluation of its fluorescence response toward Cu2+ ion. Preliminary, solvent effect, metal selectivity and metal ligand ratio were analyzed through UV-Visible study. Fluorescence response toward Cu2+ was carried to assess the fluorescent property of synthesized Schiff base. The probe exhibited a higher fluorescence enhancement in the presence of Cu2+ over other metal ions (Ni2+, Zn2+, Hg2+, Co2+, Cd2+, Al3+, Fe2+, and Pb2+). The binding stoichiometry between L and Cu2+ has been investigated using Job's plot and Benesi-Hildebrand equation and it was found that ligand L can form 1:1 L-Cu2+ complex with binding constant (K a) of 4 × 104 LM-1.

Calix[4]arene Based Dual Fluorescent Sensor for Al(3+) and S2O7 (2.).

Specific functionalized calix[4]arene based fluorescent chemosensor was synthesized for cations and anions binding efficiency examination. Receptor C4MA displayed strong affinity for Al(3+)and S2O7 (2-) with enhanced fluorescence intensity. The selective response of C4MA was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) of Al(3+)and S2O7 (2-) was calculated as 2.8 × 10(-6) M and 2.6 × 10(-7) M respectively. Sensor C4MA forms (1:1) stoichiometric complex with both Al(3+) and S2O7 (2-) and their binding constants were calculated as 12.1 × 10(4) and 8.3 × 10(3) respectively. Complexes were also characterized through FT-IR spectroscopy. Graphical Abstract ᅟ.

Calix[4]arene Based Highly Efficient Fluorescent Sensor for Au(3+) and I(.).

This approach disclose the selective fluorogenic ion sensing ability of 5,11,17,23-tetratertbutyl-25,27-bis((2hydroxynaphthylimino)1,2-ethylenediaminecarbonylmethoxy)-26,28 dihydroxycalix[4]arene (C4NSB). Binding property of receptor probed by using selected various cations and anions with conferring of results that demonstrates 'turn-off' fluorescence response and significantly high chromogenic selectivity toward Au(3+) and I(-). Furthermore, selective nature of receptor was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) for Au(3+) and I(-) was determined as 1.5 × 10(-5) and 4.5 × 10(-6) M respectively. Receptor C4NSB form (1:1) stoichiometric complex with both ions and their binding constants were calculated as 8.0 × 10(2) for Au(3+) and 15.6 × 10(2) M(-1) for I(-). Complexes were also characterized through FT-IR spectroscopy.