Radiochemistry for Preclinical Imaging Studies
George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos in Handbook of Small Animal Imaging, 2018
With regard to nomenclature, coordination complexes and organometallic compounds are distinguished. 99mTc-sestamibi is an organometallic compound because at least one ligand forms a carbon–metal bond (for 99mTc-sestamibi, it is actually all six ligands). Many other studied 99mTc complexes exhibit a mix of bonds to the metal, for example, at least one covalent bond to oxygen and coordination bonds to further ligands. An example is 99mTc-tetrofosmin with TcO2+ core and bonds to four phosphine phosphorus atoms. A pure coordination complex is 99mTc-mebrofenin (Ghibellini et al. 2008) (Choletec) composed of a TcIII center with bonds to two tertiary amino nitrogen and four carboxylate oxygen atoms (N2O4).
Dictionary
Mario P. Iturralde in Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990
Chelate compounds and chelating agents. When a metal ion combines with a group containing an electron donor, a coordination compound is formed. If the substance which combine with the metal contains two or more donor groups, or if the metal is already combined with another atom in the molecule containing the donor atom so that one or more rings are formed, the resulting structure is said to be a chelate and the attached molecule a chelating agent. Although a large number of chelating agents are known, the donor atoms are commonly restricted to nitrogen, oxygen, and sulfur.
Optimum isotherm by linear and nonlinear regression methods for lead (II) ions adsorption from aqueous solutions using synthesized coconut shell–activated carbon (SCSAC)
Published in Toxin Reviews, 2021
Onyedikachi Godwin Okpara, Osareme Mercy Ogbeide, Ozoemena Christain Ike, Kosoluchi Chisom Menechukwu, Eric Chidozie Ejike
The use of synthetic polymeric adsorbent in wastewater treatment has been investigated by several authors (Kunin 1977, Boening et al. 1980, Ferraro 1987, Ezeh et al. 2019), it general efficacy have been demonstrated on various research work which reviewed it applications relative to the basic adsorptive properties. A research work reviewing commercial applications of polymer composites toward improving environmental sustainability by water treatment and desalination has been done (Berber 2020), other related work on Pb (II) ion sorption by semicarbide immobilized polysiloxane has also been done (Ezeh et al. 2019). Other attempts were made to improve synthetic polymeric adsorbent which originally were developed on the basis of ion-exchange resins (Dedek et al. 1992). However, a review of the composition was ascertained to be; synthetic polymer and ligand. Metal ions usually bond to the ligand function to form a coordination complex.
Sonication-assisted synthesis of a new heterostructured schiff base ligand Silver-Guar gum encapsulated nanocomposite as a visible light photocatalyst
Published in Journal of Microencapsulation, 2020
Jayachandrabal Balachandramohan, Thirugnanasambandam Sivasankar
The FTIR spectra of silver nanocomposite was shown in Figure 4(b) which indicates the spectral region at 3291 cm−1 may be free solvent molecules trapped within adsorbed pores. The amide bond vibration at 1632 cm−1 of Schiff base ligand has got shifted to 1628 cm−1 in the silver nanocomposite which was due to the interaction of ligand complexation of metal coordination with the azomethine nitrogen. The dicorboxylate’s presence in the silver nanocomposites (SG1-SG4) has been confirmed by strong bands observed at 1285 and 1040 cm−1 corresponding to frequencies of the organic framework (O–C–O). The absorption band between the spectral regions of 900–1250 cm−1 corresponds to groups, C–C–O, C–OH and C–O–C (Balachandramohan and Sivasankar 2018). The characteristic peaks at 760 cm−1 corresponds to benzene rings and the stretching modes of –COO groups were identified at 697 cm−1. From the FTIR analysis, it could be concluded that the Schiff base ligand would act as the coordination complex with the guar gum and forms a metal organic framework.
Overview of Morin and Its Complementary Role as an Adjuvant for Anticancer Agents
Published in Nutrition and Cancer, 2021
Solaipriya Solairaja, Mohammad Qasim Andrabi, Nageswara Rao Dunna, Sivaramakrishnan Venkatabalasubramanian
MN is commercially marketed as Morin Hydrate. The basic structure of MN is characterized by two core aromatic ring flavan nucleus named as A and B, which are joined by a three-carbon linked γ-pyrone ring (C), forming a C6–C3–C6 skeleton unit (Supplementary Figure 1). Its molecular weight is 302.23 g/mol. MN is partially soluble in water and freely soluble in all organic solvents. It is also soluble in aqueous alkaline solution with intense yellow color which turns brown on exposure to air. It contains five hydrogen donor sites and eight hydrogen acceptor sites. It has been shown to form a fluorescent coordination complex with metals like aluminum and tin. The chemical structure of MN and other flavonoids can be distinguished by the presence of polar hydroxyl groups appended at five positions 2′,4′,3, 5, and 7 (Supplementary Figure 1). It is well known that MN shares striking structural similarities with another well-documented flavonol - Quercetin (QN). Bulk of the atomic substitutions between them are the same except the hydroxylation pattern on B-ring, which is 2′ and 4′ in MN whereas 3′ and 4′ in QN. Though QN shows better antioxidant potential than MN, it is toxic at the higher dosage. One of the main appreciations of MN is its minimal toxicity even at a higher dose expanding its potential as a better therapeutic agent. MN is also said to contain better bioavailability than QN as shown by (24). This group reported the existence of intermolecular bonds between albumin and MN conjugates, which supports its slow elimination from the body.
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