Organometallic complexes with biological molecules. X: dialkyltin(IV) and trialkyltin(IV) orotates: spectroscopic andin vivo investigations

Abstract

Several novel diorgano‐ and triorgano‐tin(IV) derivatives of orotic acid, (2,6‐dihydroxypyrimidine‐4‐carboxylic acid; H3or) have been synthesized. In the diorganotin(IV) derivatives, the orotic acid behaved either as a monoanionic or as a dianionic ligand, yielding R2Sn(H2or)2 and R2SnHor (R = Me, Bu) species, respectively, while in the triorganotin(IV) orotates only monodeprotonation of the orotic acid occurred, giving R3SnH2or (R = Me, Bu) derivatives. Structural hypotheses are proposed and discussed for the solid state based on Mössbauer and IR spectroscopic data, and for solution on 1H and 13C NMR results. Finally, investigations have been carried out in vivo, showing the inhibitor properties of all of the newly synthesized derivatives towards Ciona intestinalis embryos. In particular, in order to test the cytotoxicity in vivo of Me2SnHor, Bu2SnHor, Me3SnH2or and Bu3SnH2or, exposure to these chemicals of C. intestinalis embryos at the 2–4‐blastomere stage has been studied. The compound which exerts the highest cytotoxic effect is Bu3SnH2or at 10−5 M concentration because it blocks embryo development immediately. Me3SnH2or at 10−5 M concentration inhibits cell cleavage in the embryos at the 32‐blastomere stage, while Bu2SnHor at the same concentration gives rise to abnormal embryos. Me2SnHor, is less toxic than the trimethyl, dibutyl and tributyl analogues, since 40% of the total number of treated embryos resulted in normal larvae. The ligand does not affect embryonic development significantly. The results seem to indicate that the chemical species under investigation, especially Bu3SnH2or, interfere with polymerization of tubulin during the process of cell division in early embryo development. Copyright © 1999 John Wiley & Sons, Ltd.

Theoretical and spectroscopic studies of lanthanum (III) complex of 5-aminoorotic acid

“…Furthermore, the spectra in the frequency region below 600 cm À1 are of particular interest, since they provide information about metal-ligand vibrations. The new band at 617 cm À1 and the new shoulder at 521 cm À1 present only in the IR spectrum of the complex, which can not be observed in its Raman spectrum, can be due to the La-O interactions [48,50,95]. In the low wavenumbers region of the Raman spectrum of the complex (Fig.…”

“…5 and 6, were analyzed by comparing these modes with those from the literature [44,48,50,[91][92][93][94][95] in combination with the results of our DFT calculations (i.e., harmonic vibrational wavenumbers and their Raman scattering activities). In the Table 3 the selected calculated and experimental IR and Raman data together with their tentative assignment are given.…”

“…5 and 6). The assignment of the C-H and N-H bands is quite difficult because they appear overlapped in the same spectral region, and the involvement of these groups in hydrogen bonds affects their wavenumbers and produces a relevant band broadening [48,[91][92][93][94][95]. In the IR spectra, the strong band at 3457 cm À1 (HAOA) and the medium bands at 3479 and 3448 cm À1 (La(III) complex) were assigned to the N-H stretching modes from the pyrimidine rings (Table 3) [81,85,100], while the bands at 3333 cm À1 and 3044 cm À1 in the IR spectrum of HAOA as well as the bands at 3339 cm À1 , 3263 cm À1 , and 3038 cm À1 (IR spectrum of La(III) complex) were attributed to the C-H stretching modes [44,85,101] (Fig.…”

Theoretical and spectroscopic studies of 5‐aminoorotic acid and its new lanthanide(III) complexes

“…The newly appeared bands in the IR spectra of the complexes, at 620 cm 1 (Ce(III) complex) and at 619 cm 1 (Nd(III) complex), as well as the new shoulders at 548 cm 1 (Ce(III) complex) and 551 cm 1 (Nd(III) complex), which cannot be observed in the Raman spectra, can be due to metal-oxygen interactions. 48,50,66 In the low wavenumber region of the Raman spectra of the lanthanide complexes of H 4 L (Fig. 5), bands that can be due to the metal-oxygen vibrations 78 -82 are the band at 425 cm 1 (Ce(III) complex) and the peak at 427 cm 1 (Nd(III) complex), which are increased in relative intensities in comparison to the Raman spectrum of the ligand.…”

“…Owing to electron transfer from the carboxyl ion to lanthanides (III), changes of chemical shifts were observed for the neighboring carbon atoms of Ce(III) complex and they confirmed the expected coordination of the ligand through the oxygen atoms of the carboxyl ion. 57,66 The literature values 101 of the 13 C chemical shifts of orotic acid are included in Table 5 for comparison.…”