Investigation of calcium silicate as a natural clay-based sunblock: Formulation and characterization.

Background: Sunlight exposure causes several types of health issues to humans, and in particular, it affects especially the skin. Among the most common harmful issues developed by UV exposure are erythema, pigmentation, and lesions in DNA, which may lead to cancer. These long-term effects can be minimized with the use of sunscreen.

Synthesis and Toxicity Evaluation of Some N4-Aryl Substituted 5-Trifluoromethoxyisatin-3-thiosemicarbazones.

A series of twenty one N4-aryl substituted 5-trifluoromethoxyisatin-3-thiosemicarbazones 3a-3u was synthesized by the reaction of trifluoromethoxyisatin 1 with different arylthiosemicarbazides 2 in aqueous ethanol (50%), containing a few drops of acetic acid. Their structures were established on the basis of analytical (CHN) and spectral (IR, 1H-NMR, EIMS) data. All the synthesized compounds were evaluated for their toxicity potential by a brine shrimp lethality bioassay.

1-[2-Oxo-5-(trifluoro-meth-oxy)indolin-3-yl-idene]-4-[4-(trifluoro-methyl)-phen-yl]thio-semicarbazide.

In the title compound, C(17)H(10)F(6)N(4)O(2)S, an intra-molecular N-H⋯N hydrogen bonds forms an S(5) ring whereas N-H⋯O and C-H⋯S inter-actions complete S(6) ring motifs. The dihedral angle between the fused ring system and the phenyl ring is 6.68 (8)°.

N-{2-[N-(4-Methyl-phen-yl)oxamo-yl]phen-yl}propanamide.

The title compound, C(18)H(18)N(2)O(3), is the product of the heterocyclic ring cleavage at position 2 of 1-propionylisatin. Two centrosymmetric cyclic motifs, viz. R(2) (2)(14) and R(2) (2)(18), are formed by N-H⋯O hydrogen bonds with the propanamide and amino-phenyl units, respectively, as the N-H donors.

4-(3-Nitro-phen-yl)-1-(2-oxoindolin-3-yl-idene)thio-semicarbazide.

In the title compound, C(15)H(11)N(5)O(3)S, intra-molecular N-H⋯N hydrogen bonding forms an S(5) ring motif, whereas N-H⋯O and C-H⋯S inter-actions type complete S(6) ring motifs. The 2-oxoindoline and 3-methoxy-phenyl rings are almost planar, with r.m.

4-(3-Methoxy-phen-yl)-1-(2-oxoindolin-3-yl-idene)thio-semicarbazide.

In the title compound, C(16)H(14)N(4)O(2)S, intra-molecular N-H⋯N hydrogen bonding forms an S(5) ring, whereas N-H⋯O and C-H⋯S inter-actions complete S(6) ring motifs. In the crystal, mol-ecules form inversion dimers due to N-H⋯O inter-actions. The dimers are inter-linked through N-H⋯S hydrogen bonds and π-π inter-actions occur with a centroid-centroid distance of 3.

4-(5-Chloro-2-methyl-phen-yl)-1-[2-oxo-5-(trifluoro-meth-oxy)indolin-3-yl-idene]thio-semicarbazide.

The asymmetric unit of the title compound, C(17)H(12)ClF(3)N(4)O(2)S, contains two mol-ecules, which differ in their planarity and hydrogen bonding. In one mol-ecule, the 2-oxoindolin (C(8)/N/O A), thio-semicarbazide (N(3)/C/S B) and 5-chloro-2-methyl-phenyl (C(7)/Cl C) units are planar with r.m.