Experimental and theoretical study on the interaction of dopamine hydrochloride with H2O

Computational Study of Doping in Dopamine with Halogens to Control Optical and Spectroscopic Properties

In this research, a comprehensive study of dopamine was conducted using the theoretical first principles method due to its crucial importance as a hormone for the neurotransmission process in the animal body. Many basis sets and functionals were used for optimization of the compound to attain stability and find the appropriate energy point for the overall calculations. Then, the compound was doped with the first three members of the halogen family (fluorine, chlorine, and bromine) to analyze the effect of their presence in terms of change in their electronic properties, such as band gap and density of states, and spectroscopic parameters, such as nuclear magnetic resonance and Fourier transform infrared. It was found that the band gap of the system changes depending on the doping of halogens.

Experimental and Theoretical Study on the Interaction of P-Aminophenol Hydrochloride with H2O

UV-Vis absorption spectra, cyclic voltammetry and 1H nuclear magnetic resonance (1H NMR) spectra were applied to explore the hydrogen bond interactions of p-aminophenol hydrochloride (PAH) with H2O. The results indicated the hydrogen bonds were formed in PAH–H2O system. The anodic/cathodic peak potentials and UV-Vis absorption bands of PAH in H2O could be affected due to the interactions. The results of density functional theory, atoms in molecules theory and natural bond orbital analyses further confirmed the existence of hydrogen bonds between the phenolic hydroxyl, –NH3 + protons and Cl− of PAH and H2O. Furthermore, the π-π stacking was suggested between PAH benzene rings from the 1H NMR spectra at higher concentrations.

Structural confirmation and spectroscopic study of a biomolecule: Norepinephrine

The present work deals with the conformational and vibrational spectroscopic study of an important bio-molecule named norepinephrine in gas phase. The FTIR and FTRaman spectrum of norepinephrine in amorphous form were recorded in wavenumber range 4000-400 cm^-1 and 4000-50 cm^-1 respectively. We have investigated twenty-seven stable conformational structures of norepinephrine molecule. All the calculations have been done using Density Functional Theory with exchange functional B3LYP incorporated with the 6-31++G(d, p) basis set. The effect of hydrochloride on different bond lengths, bond angles and dihedral angles in the most stable conformer has also been studied. The total potential energy distribution for both the most stable conformer and the most stable conformer in hydrochloride was performed with the help Normal coordinate analysis method. Most of the calculated vibrational frequencies are in good agreement with the experimental frequencies. The natural bond orbital analysis was also performed to ensure the stability of electronic structures of norepinephrine. To know chemical reactivity of norepinephrine molecule we have calculated the energy gap between HOMO and LUMO orbitals and it has found above 5 eV in all the conformers.

Determination of dopamine hydrochloride by host-guest interaction based on water-soluble pillar[5]arene

The supramolecular interaction between the water-soluble pillar[5]arene (WP[5]) as host and dopamine hydrochloride (DH) as guest was studied by spectrofluorometry. The fluorescence intensity of DH gradually decreased with increasing WP[5] concentration, and the possible interaction mechanism between WP[5] and DH was confirmed by ¹H NMR, 2D NOESY, and molecular modelling. Based on significant DH fluorescence, a highly sensitive and selective method for DH determination was developed for the first time. The fluorescence intensity was measured at 312nm, with excitation at 285nm. The effects of pH, temperature, and reaction time on the fluorescence spectra of the WP[5]-DH complex were investigated. A linear relationship between fluorescence intensity and DH concentration in the range of 0.07-6.2μgmL^-1 was obtained. The corresponding linear regression equation is ΔF=25.76 C+13.56 (where C denotes the concentration in μgmL^-1), with the limit of detection equal to 0.03μgmL^-1 and the correlation coefficient equal to 0.9996. This method can be used for the determination of dopamine in injection and urine samples. In addition, the WP[5]-DH complex has potential applications in fluorescent sensing and pharmacokinetics studies of DH.