A DFT study on the metal ion selectivity of deferiprone complexes

In this work, systematic density functional theory (DFT) calculations were performed to study the interactions of various metal ions (Al³⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) and the clinically useful chelating agent called deferiprone (DFP) at the M05-2X/6-31G(d) level of theory. The thermodynamic parameters of metal-deferiprone complexes were determined in water. Based on the obtained data, the theoretical binding energy trend is as follows: Al³⁺ > Fe³⁺ > Cu²⁺ > Ni²⁺ > Co²⁺ > Zn²⁺, confirming that [Al(DFP)₃] has the most interaction energy. Moreover, Natural bond orbital analysis was employed to determine and analyze the natural charges on different atoms and charge transfer between the metal ions and ligands (oxygen atoms) as well as the interaction energy (E(2)) values. The calculated value of ƩE(2) (donor-acceptor interaction energy) for [Al(DFP)₃] complex is higher than other complexes, which is according to energy analysis. To confirm the type of effective interactions and bonding properties in the water, the quantum theory of atoms in molecules (QTAIM) analysis was applied. QTAIM analysis confirmed that the strongest M - O bond is found in the [Al(DFP)₃] complex. The calculated topological properties at the bond critical points, such as the ratio of the kinetic energy density to the potential energy density, -G(r)/V(r), electronic energy density, H(r), confirm that M - O bonds in the Al-deferiprone complex are non-covalent, while in other complexes, they are electrostatic and partially covalent.

Metal ions doped into merocyanine form of coumarin derivatives: nonlinear optical molecular switches

In the present study, DFT calculations are carried out on domestically designed 7-methyl-2-phenyl-5'H-spiro[chromene-4,2'-chromeno[3,4-e][1,3]oxazin]-5'-one spiropyran and merocyanine derivatives to recognize alkali and alkaline earth metal ions. Detection of these metal ions can be attained by exploiting the variation of the second-order nonlinear optical properties. Merocyanine forms of these derivatives exhibit the ability to complex with different metal ions (Li⁺, Na⁺, K⁺, and Ca²⁺), which is associated with large contrasts in the hyper-Rayleigh scattering (HRS) response as a function of metal size and charge. Interestingly, in this study, Mero-Li⁺ shows significant nonlinear optical response with dynamic HRS first hyperpolarizability amounting to 7607 a.u., which is about nine times higher than its corresponding spiro form (846 a.u.) at the CAM-B3LYP/6-311G* level of theory. The present investigation clarifies the effect of metal nature on the enhancement of the first hyperpolarizability between the closed and open forms of the studied coumarin derivatives. Graphical abstract The coumarin-based compound 3 demonstrate the higher second-order NLO responses as a function of metal cation size and charges. Complexation of smaller alkali metal ions leads to the formation of stronger metal-ligand bonds, larger geometrical relaxations and significant enhancement of the HRS first hyperpolarizabilities. This present investigation elucidates the effect of metal nature on the enhancement of the first hyperpolarizability between the closed and open forms of studied coumarin derivatives.

A cation-selective and anion-controlled benzothiazolyl-attached macrocycle for NLO-based cation detection: variational first hyperpolarizabilities

The addition of Hg²⁺ leads to a significant decrement in the NLO response with respect to the corresponding macrocycle L.

A Cryptand Metal-Organic Framework as a Platform for the Selective Uptake and Detection of Group I Metal Cations

The metal-organic framework (MOF) complex (H₃ O)₂ [Zn₄ (ur)(Hfdc)₂ (fdc)₄ ] (1, ur=urotropine, H₂ fdc=furan-2,5-dicarboxylic acid) incorporates cryptand-like cavities, which can be used to separate and detect Rb⁺ and Cs⁺ optically. This is the first example of the effective employment of a MOF material for optical detection of these cations.

Variational first hyperpolarizabilities of 2,3-naphtho-15-crown-5 ether derivatives with cation-complexing: a potential and selective cation detector

When the crown ether and its cation derivatives display obvious contrasts in NLO properties, the NLO-based detection of cations is achieved.

Exocyclic self-assembly behavior of carboxylic acid and lariat ether macrocyclic hosts: regulation by pendent arm

An exocyclic supramolecular building block through O–H⋯N hydrogen bonding interaction for the assembly of di-sidearm dibenzo-diazacrown ethers bearing a flexibility sidearm with PTA acid.