Synthesis,spectroscopic findings and crystal engineering of Pb(ii)–Salen coordination polymers,and supramolecular architectures engineered by σ-hole/spodium/tetrel bonds: a combined experimental and theoretical investigation

Spontaneous self-assembly is one of the available synthetic routes to achieve structurally versatile and unique crystal complexes with selected metal–ligand combinations in the spirit of pseudohalides. In this endeavour, we designed a novel 1D coordination polymer (CP), [(Cd)(Pb)(L)(η¹-NCS)(η¹-SCN)]_n (1), using a compartmental Salen ligand (H₃L) in the presence of NaSCN. The characterization of the CP was accomplished using several spectroscopic techniques: MALDI-TOF, PXRD, SEM, EDX mapping, and single-crystal X-ray crystallography. The CP crystallizes in the monoclinic space group P2₁/c with Z = 4. SCXRD reveals Cd(ii) and Pb(ii) metal ions fulfilled distorted square pyramidal and hemi-directed coordination spheres. Cd(ii) is placed in the inner N₂O₂ and heavier Pb(ii) in the outer O₄ compartments of the de-protonated form of the ligand [L]²⁻. Supramolecular interactions in the intricate crystal structure produced attractive molecular architectures of the compound. The flexible aliphatic –OH pendent group coordinates with the Pb(ii) ions. This unique binding further elevates the supramolecular crystal topographies. The supramolecular interactions were authenticated by Hirshfeld surface analysis (HSA). The observation of the recurring unconventional tetrel bonds was rationalized by DFT calculations and surface plots of molecular electrostatic potential (MEP). In the 1D polymeric chain in the complex, the O-atom of the –OH groups shows a tetrel bonding interaction with the Pb atom. We have found that the combination of QTAIM/NCI and QTAIM/ELF plots helps reveal the nature of these contacts. Moreover, the QTAIM/ELF plot determines the donor–acceptor interaction between the O-atom and the Pb atom, establishing the σ-hole. Agreeably, the σ-hole interaction also helps Pb(ii) serve as a Lewis acid in the complex. Finally, spodium and tetrel bonds are formed, possible thanks to a hemi-directional coordination sphere of the Pb atoms in the polymer described.

We report σ-hole interaction/spodium/tetrel bonding and other non-covalent interactions in a heteronuclear Pb(ii)–Salen coordination polymer using DFT, HSA, QTAIM/NCI, and QTAIM/ELF plots. The non-covalent interactions predominantly drive the formation of extended architectures.     

FSH β-subunit mutations in two sisters: the first report from the Indian sub-continent and review of previous cases

Isolated FSH deficiency due to mutations in the gene for β-subunit of FSH is an extremely rare autosomal recessive disease of which only eleven cases have been reported so far. The clinical features include absent breast development and primary amenorrhea in females and azoospermia with normal testosterone levels in males. In this study we report two Kashmiri sisters born to native Kashmiri consanguineous parents with failure of onset of puberty. Hormonal evaluation revealed undetectable serum FSH and estradiol and high LH. Genetic analysis of FSH β-gene identified one nonsense mutation (c.343C?>?T:p. Arg115Stop) in exon 3. The two sisters were homozygous for this nonsense mutation while the parents were heterozygous. Incorporation of a stop codon at 115 codon position is predicted to result in the formation of truncated FSH β protein, lacking 14 amino acid from the carboxy-terminus (p.Arg115Stop). Very recently, this same mutation was reported for the first time in a Chinese male. Ours is the first ever report of any FSH β-subunit mutation from the Indian sub-continent and this particular mutation in any female from anywhere in the world. We conclude and emphasize that this diagnosis should be considered in girls with delayed puberty and selective deficiency of FSH.     

Different Growth Responses to Recombinant Human Growth Hormone in Three Siblings with Isolated Growth Hormone Deficiency Type 1A due to a 6.7Kb Deletion in the GH1 Gene

Isolated growth hormone deficiency (IGHD) type 1A is a rare, autosomal recessive disorder caused by deletion of the GH1 gene and characterized by early onset severe short stature and typical phenotype. Lack of exposure to GH during fetal life often leads to formation of anti-GH antibody following exposure even the least immunogenic recombinant human GH (rhGH). Some patients with circulating anti-GH antibodies demonstrate lack of growth response to GH while others do not. However, the clinical significance of this antibody is unclear; hence testing is not routinely recommended. Three siblings, born of a consanguineous union, were referred with severe short stature. They were evaluated and IGHD was diagnosed in all of them. Genetic analysis revealed that all three had homozygous 6.7 Kb deletion in GH1 gene, while their parents displayed a pattern of heterozygous 6.7 Kb deletions. rhGH was started at 10, 6 and 1.58 years of age, respectively. Growth and hormonal parameters were monitored throughout the course of treatment. The eldest sibling demonstrated expected growth velocity (9.5 cm/year) for the first year of rhGH that rapidly waned thereafter (2.5 cm/year). The youngest sibling experienced excellent growth response even after the third year (10.3 cm/year) while the middle sibling displayed sub-optimal response from rhGH initiation (6.3 cm/year). Change of rhGH brand did not work in the two elder sisters. Such a different growth response with rhGH in three siblings harbouring similar genetic abnormality has not been described previously.