The complexes [Eu(12-crown-4)(terpy)(H₂O)]3Cl, [Eu(15-crown-5)(terpy)]3Cl, [Tb(12-crown-4)(terpy)(H₂O)]3Cl, [Tb(15-crown-5)(terpy)]3Cl, [Gd(12-crown-4)(terpy)(H₂O)]3Cl and [Gd(15-crown-5)(terpy)]3Cl (terpy = 2,2′,6′,2′′-terpyridine) were synthesized and characterized by CHN elemental analysis, infrared spectroscopy and fluorescence spectroscopy. Emission spectra were obtained on both, solid state and aqueous solutions for europium and terbium complexes. The complexes exhibit good emission, even in aqueous solution, enhancing their potential for biological applications. The reduction of emission intensity, from solid state to aqueous solution, is lower for europium complexes, in comparison to terbium complexes. The [Eu(12-crown-4)(terpy)(H₂O)] · 3Cl complex exhibits an emission lifetime of 0.64 ms while [Eu(15-crown-5)(terpy)] · 3Cl exhibits a value of 0.38 ms. Furthermore, the 15-crown-5 complex emission intensity is about 3.8 times larger than the emission intensity of the 12-crown-4 complex. This ratio (3.8) is the same as observed for the A _RAD and A _NRAD for the aqueous solutions: 1225.5/339.5 = 3.6. The aqueous solution quantum yield is higher for [Eu(12-crown-4)(terpy)(H₂O)]3Cl in comparison with [Eu(15-crown-5)(terpy)]3Cl, suggesting that 12-crown-4 exhibits a more suitable ratio than 15-crown-5.

In this communication, the synthesis, characterization, and hydrogen sulfide (H₂S) adsorption of Rhodamine B modified kaolinite are reported. The modified matrices were prepared by a cation exchange process. The pure and modified matrices were characterized by X-ray diffractometry, FTIR-spectroscopy, and thermogravimetry. The total amount of adsorbed H₂S (gravimetric data) can be described as: pure kaolinite (2.6 mg/g) and Rodhamine B modified kaolinite (10.1 mg/g). So, the H₂S adsorption capacity of kaolinite is increased by almost 300% by Rhodamine B modification.

In this work, we presented new empirical equations to calculate the lattice energy values of groups 1 and 2 halides based on absolute hardness values of cations and anions forming the ionic compound.In the given equations, r+ and r+2 = cation radius (pm); η+ and η+2 = cation absolute hardness (eV) and η- = anion absolute hardness (eV). Here, it should be noted that calculated lattice energy values for mentioned ionic compounds are in good agreement with the reference values obtained from the literature.

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The following empirical equation was derived: U_POT = (−0.494r⁺ + 122.392)(η⁺ + η⁻) − 109.514η⁺ + 1191.694 kJ mol⁻¹, where r⁺ is the cation radius (pm), η⁺ is the absolute hardness of the cation, and η⁻ is the absolute hardness of the anion. This equation in conjunction with Kapustinskii lattice energy values for element 119 halides was employed to calculate the first and second ionization energies of 4.04 and 20.72 eV, respectively; for the monocation 119⁺, r⁺ = 202.2 pm, η⁺ = 8.34 and η⁺ = 12.38. Furthermore, the second ionization energy for francium was calculated as 23.80 eV.