A new 1,3-lower rim-lipoic acid appended calix[4]arene (L) has been synthesized and characterized by different spectral techniques. Lipoic acid functionality helps L to anchor onto a noble metal surface, and in the present case these are the gold nanorods (GNRs). As the conjugate of calix[4]arene acts as a host due to the presence of its arene cavity, pyridinium containing guests have been explored to study their complexation, since the pyridinium containing molecules will accumulate in mitochondria in cells. The host−guest complexation has been explored in solution by 1 H NMR, ESI-MS, UV−vis, and fluorescence spectral titration studies. The loading of host and the guest onto the GNR surface has been analyzed by spectroscopy and microscopy and found that their combination results in nanocomplexation. The presence of pyridinium functionality on the guest leads to targeted delivery to mitochondria of GNR nanocomposites as shown by confocal laser scanning microscopy imaging. The nanocomplex has been studied for cancer cell imaging and laser-induced cell killing with the help of plasmonic gold nanorods. When excited at the longitudinal SPR band of GNRs using laser (λ = 633 nm), cancer cell killing was observed due to laser-induced cell death. The flow cytometry studies supported ∼97% killing when the GNR-nanocomplex administered HeLa cells were irradiated under laser light for 10 min, which is a ∼4 fold increase in their cell as compared to the study carried out in the absence of laser light irradiation, and this has been partly attributed to the greater internalization of these into cells.

A triazole-derivatized, spiro-indoline-linked, 1,3-di-derivative of calix[4]arene ( L ) has been synthesized to take advantage of its ion-binding capability in the ring-open form. Indeed, the spiro-indoline moiety is well known for its photochromic, acidochromic, and metallochromic properties. Therefore, the L has been explored for Cu 2+ binding, cell imaging, and anticancer activity of the corresponding complex since Cu 2+ complexes are known for such activity. The conversion from the closed to open form of L is expedited by light or proton, while the metal ion can open as well as stabilize it. The open form of L showed binding of Cu 2+ ratiometrically as demonstrated by absorption and fluorescence spectroscopy. This leads to the formation of 1:1 complex with a binding constant of (6.9 ± 2.3) × 10 5 M –1 , with the lowest detection limit being 1.9 nM. In the complex, the Cu 2+ is bound by two triazole-N and two phenolic-O groups resulting in a distorted tetrahedral coordination core of CuN 2 O 2 as demonstrated based on density functional theory studies. To form such coordination core, the arms underwent considerable changes in some of the dihedral angles. The binding of Cu 2+ to L induces self-assembly of L by varying from simple particles to rodlike structures when bound to Cu 2+ . The on–off fluorescence intensity of L and its Cu 2+ -bound species are responsible for imaging cancer cells. The L shows red fluorescence in MDA-MB-231 cancer cells by targeting mitochondria as proved based on the colocalization study carried out using MitoTracker Green. While the L alone is nontoxic to cancer cells, the presence of Cu 2+ brings cell death to an extent of 90% with an IC 50 value of 165 nM by bringing a substantial quench in the fluorescence of L . A shift of population from G 0 /G 1 and G 2 M phases to the Sub-G 1 phase was observed as the concentration of the complex was increased, indicating cell death as studied by fluorescence-activated cell sorting. Thus, the present work clearly proved that a calix[4]arene functionalized at the lower rim with spiro-indoline moieities when complexed with Cu 2+ acts as an efficient anticancer agent and is capable of imaging cancer cells.

Copper phosphate nanoflowers (CuPNFs) have been synthesized in the presence of different aromatic phenanthroline derivatives (Ln) leading to the inorganic-organic hybrid materials (Ln-CuPNFs). The studies revealed that the morphology of...

Host-guest chemistry, particularly of supramolecules, has been an intriguing topic for researchers for a long time due to its multiplicative applications ranging from chemical to biological to materials science. Supramolecules,...

A triazole appended benzaldehydic lower rim derivative of calix [4]arene (L) has been synthesized and was thoroughly characterized. In CH 3 CN solution, the L showed greater sensitivity for Fe 3 + by a 5-fold increase in the absorbance and 37% quenching in the fluorescence intensity, by forming a 1:1 complex. The Fe 3 + induces aggregation in L as studied by microscopy. The Langmuir film formed at the air-water interface was characterized by pressure-area isotherm and Brewster angle micrographs, both in the presence and absence of metal ions. The Langmuir films of pure L, {L + Al 3 + } and {L + Zn 2 + } were transferred onto H-terminated Si-wafer and characterized using Atomic Force Microscopy, contact angle, Grazing Incidence Fourier Transform Infrared Spectrscopy and X-ray Photoelectron Spectroscopy. The study resulted selective binding of Al 3 + to the Langmuir film of L among the nine metal ions studied. Thus, the calix[4]arene-conjugate L is sensitive and selective to Fe 3 + in acetonitrile solution whereas to Al 3 + in Langmuir film and hence acts as an ion switch depending upon the physical state of L.designed in the light of the following aspects: (i) The calix [4] arene core is required for the presence of arene compartment and also to provide a platform in order to build the arms with [a] R.