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This paper investigates the reactivity and optical properties of transition metal-incorporated organoantimony(V) clusters prepared by a solvothermal route. The detailed structural characterization of novel heterometallic M 2 Sb 4 oxo clusters is reported herein. Single crystal X-ray diffraction revealed the formation of hexanuclear organoantimony(V) based oxo clusters [( p -ClC 6 H 4 Sb) 4 V 2 (O) 2 (μ 3 -O) 2 (μ 2 -O) 2 ( t -BuPO 3 ) 4 (μ 2 -OCH 3 ) 4 ] (1), [M 2 ( p -iPr-C 6 H 4 Sb) 4 (μ 3 -O) 2 (μ 2 -O) 2 (μ 2 -OCH 3 ) 4 ( t -BuPO 3 ) 4 (py) 2 ]· x CH 3 OH, where M = Mn, x = 2 (2), Co, x = 1 (3), Ni, x = 2 (4) and Cu, x = 2 (5). The magnetic behaviour of the clusters was probed by magnetic susceptibility measurements. Optical absorption studies showed that bandgap reduction can be achieved by incorporating an appropriate transition metal into the homometallic Sb 6 oxo cluster.

The reactions of [Zn 3 Cl 2 (3,5-Me 2 PzH) 4 ( t -BuPO 3 ) 2 ] with organostibonic acid in varying reaction conditions have been investigated. Single-crystal X-ray diffraction studies reveal the formation of [Zn 2 ( p -ClC 6 H 4 Sb) 2 (O) 2 (OCH 3 ) 2 ( t -BuPO 3 ) 3 (py) 2 ] ( 1 ), [Zn 2 ( p -ClC 6 H 4 Sb V ) 4 (Sb III ) 2 (O) 8 ( t -BuPO 3 H) 4 ( t -BuPO 3 ) 2 (py) 2 Cl 2 ] ( 2 ), and [Zn 2 (RSb) 4 (O) 4 (OCH 3 ) 4 ( t -BuPO 3 ) 4 (py) 2 ], where R = p -ClC 6 H 4 ( 3 ) and R = p -iPrC 6 H 4 ( 4 ), respectively. Interestingly, in the synthesis of 2 , complete dearylation of organoantimony moieties followed by C-F bond formation, a reduction from Sb (V) to Sb (III), and Sb···Cl weak intermolecular interactions have been observed. ESI-MS studies suggested that clusters 1 - 4 maintained their structural integrity in the solution state also. Solution NMR studies ( 1 H, 31 P, and 13 C) support well the observed solid-state structures. 1 - 4 were tested for antibacterial activity using a microdilution assay. 1 and 4 showed the best activity with lower MIC values (0.78-6.25 μg/mL) against all the tested pathogens. The total antioxidant activity of 1 - 4 was evaluated through the phosphomolybdenum assay, which showed a total antioxidant activity ranging from 28.96 to 86.46 mg AAE/g compound with the ascorbic acid standard.

Isolation and structural characterization of novel organoantimony(V)-based oxo clusters are reported. (RSb) 4 (OH) 4 ( t -BuPO 3 ) 6 and (RSb) 2 (O)( t -BuPO 3 H) 6 independently in the presence of pyridine under solvothermal conditions afford the hexanuclear organoantimonate clusters [(RSb) 6 (μ 3 -O) 2 (μ 2 -O) 6 ( t -BuPO 3 ) 4 ], where R = p - i -PrC 6 H 4 ( 1 ), p -ClC 6 H 4 ( 2 ). Further, reaction of organostibonate phosphonate with Ti(O i Pr) 4 in the presence of pyridine under solvothermal conditions afforded the mixed-metal titanium stibonate hexanuclear clusters [(RSb) 2 Ti 4 (μ 3 -O) 2 (μ 2 -O) 2 ( t -BuPO 3 ) 4 (μ-OCH 3 ) 4 (OCH 3 ) 4 ], where R = p - i -PrC 6 H 4 ( 3 ), p -ClC 6 H 4 ( 4 ). Band gap measurements were performed on 1 - 4 . They reveal a remarkable reduction in the band gap on moving from the heavier main-group-based oxo cages ( 1 and 2 ) to the titanium-incorporated oxo cages ( 3 and 4 ).

The reaction of organobismuth precursors with trityl- H -phosphinic acid in varying reaction conditions afforded colorless crystals, whose single crystal X-ray characterization revealed the formation of monomer {(Ph 3 Bi)[(Ph 3 C)(H)PO 2 ] 2 }· 3 / 2 (CH 3 CN) 2 . 1 / 2 H 2 O ( 1 ) and butterfly shaped tetranuclear cluster Bi 4 (μ 3 -O) 2 [(Ph 3 C)(H)(PO 2 )] 8 ·2CH 2 Cl 2 · 1 / 2 CH 3 CN.2H 2 O ( 2 ). The reaction of titanium isopropoxide with two different phosphinic acids trityl- H -phosphinic acid and cyc P(O)(OH) led to isolation of cubane type octahedral complex {Ti 8 (μ 2 -O) 8 (μ 2 -OH) 4 [(Ph 3 C)(H)PO 2 ] 12 }[3C 7 H 8 ] ( 3 ) and hexanuclear complex Ti 6 (μ 2 - cyc PO 2 ) 9 (μ 2 -O) 6 (μ 2 -OH) 3 ·4CH 3 CN·4H 2 O ( 4 ) respectively.

The Dracaena resin is widely used in traditional medicine as an anticancer agent, and benzofuran lignan is the active component. In this report, we provide evidence that the synthetic derivative of benzofuran lignan (Benfur) showed antitumor activities. It induced apoptosis in p53-positive cells. Though it inhibited endotoxin-induced nuclear factor kappaB (NF-kappaB) activation in both p53-positive and -negative cells, the activation of caspase 3 was observed in p53-positive cells. It showed partial cell death effect in both p53-positive and -negative cells through inhibition of NF-kappaB. Cell cycle analysis using flow cytometry showed that treatment with this novel benozofuran lignan derivative to Jurkat T-cells, but not U-937 cells, resulted in a G2/M arrest in a dose- and time-dependent manner. It increased amounts of p21, p27, and cyclin B, but not phospho-Rb through p53 nuclear translocation in Jurkat T-cells, but not in U-937 cells. It inhibited amounts of MDM2 (murine double minute 2) by repressing the transcription factor Sp1, which was also proved in silico. It induced cell death in tumor cells, but not in primary T-cells. Overall, our data suggest that Benfur-mediated cell death is partially dependent upon NF-kappaB, but predominantly dependent on p53. Thus, this novel benzofuran lignan derivative can be effective chemopreventive or chemotherapeutic agent against malignant T-cells.