Catalytic Synthesis and Characterization of Biodegradable ...
Catalytic Synthesis and Characterization of Biodegradable ...
Catalytic Synthesis and Characterization of Biodegradable ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Chapter 2<br />
was first synthesized according to the method described in a previous report 29 with some<br />
modifications as follows. A solution <strong>of</strong> cobalt acetate tetrahydrate (0.75 g, 3.0 mmol) in<br />
methanol (200 mL) was added to a solution <strong>of</strong> the lig<strong>and</strong>, H2L 1 (1.81 g, 3.0 mmol), in CH2Cl2<br />
(20 mL) via a cannula under an atmosphere <strong>of</strong> argon. A brick-red precipitate was observed<br />
before all <strong>of</strong> the cobalt acetate solution was added. The residue on the wall <strong>of</strong> the reaction<br />
flask was rinsed with methanol (20 mL), <strong>and</strong> the collected mixture was allowed to stir for a<br />
further 15 min at room temperature, <strong>and</strong> then for 30 min at 0 . The solids were collected by<br />
filtration <strong>and</strong> rinsed with cold (0 ) methanol (3 × 50 mL) before drying at 60 in a vacuum<br />
for 24 h. The product L 1 -Co II was obtained in 95% yield. FT-IR (KBr): 1610 (s, C=N), 1595<br />
(s, Ar–ring), 1527 (s, Ar–ring), 1254 (s, C–O), 572 cm -1 (w, Co–O). ESI-MS: m/z = 603.6<br />
(C36H52N2O2Co) + .<br />
(2,4-Dinitrophenolato)(R,R)-N,N�-(1,2-cyclohexene)bis(3,5-di-tert-butylsalicylideneiminat<br />
o)]cobalt(III) (L 1 -Co III -dnp) was synthesized according to a method described in the<br />
literature with modifications as follows. 22, 29 To a stirred solution <strong>of</strong> L 1 -Co II (1.48 g, 2.0 mmol)<br />
in CH2Cl2 (150 mL), 2,4-dinitrophenol (0.368 g, 2.0 mmol, 1 equiv.) in CH2Cl2 (20 mL) was<br />
added. The solution was stirred under dry oxygen at room temperature for 60 min. The<br />
solvents were removed under vacuum to leave a crude dark solid in an approximately 100%<br />
yield. The residue was further rinsed with a mixture <strong>of</strong> diethyl ether <strong>and</strong> hexane, <strong>and</strong> then<br />
dried at 60 under vacuum for 24 h, yielding a dark needle-like crystal (1.47 g, 94%). FT-IR<br />
(KBr): 1624 (s, C=N), 1610 (s, Ar–ring), 1566 (w, N=O), 1525 (s, Ar–ring), 1327 (s, N=O),<br />
1252 (s, C–O), 1063 (w, C–N), 571 cm -1 (w, Co–O). C42H55N4O7Co (786.8): Calcd. C 64.11,<br />
H 7.05, N 7.12; Found C 64.01, H 7.01, N 6.94. ESI-MS: m/z = 786.3, (C42H55N4O7Co) + ,<br />
603.5 (C36H52N2O2Co) + , 183.2 (C6H3N2O5) - . Crystal data for L 1 -Co III -dnp: C42H55CoN4O20,<br />
M = 786.83, Triclinic space group P 1.<br />
a = 11.2788(13) Å, b = 14.4552(17) Å, c = 14.5806(17)<br />
Å, � = 90.382(2), = 108.936(2), � = 111.141(2), V = 2076.5(4) Å 3 , Z = 2, Dcalcd = 1.258 g<br />
cm -3 , (Mo K ) = 0.466 mm -1 . The data were collected at 293 K. Of the 11165 reflections,<br />
7503 were unique (Rint = 0.017). The non-hydrogen atoms were anisotropically refined. The<br />
hydrogen atoms were geometrically positioned <strong>and</strong> refined as riding atoms. The final cycle <strong>of</strong><br />
the full-matrix least-squares refinement converged with R = 0.0447 <strong>and</strong> Rw = 0.1040 based on<br />
6046 reflections with I > 2(I).<br />
(2,4-Dinitrophenolato)[N,N�-ethylenebis(3,5-di-tert-butylsalicylideneiminato)]cobalt(I<br />
II) (L 2 -Co III -dnp) was synthesized by a procedure similar to that <strong>of</strong> L 1 -Co III -dnp. Yield: 89%.<br />
IR (KBr): 1626 (s, C=N), 1596 (s, Ar–ring), 1569 (w, N=O), 1521 (s, Ar–ring), 1331 (s, N=O),<br />
1257 (s, C–O), 1065 (w, C–N), 583 cm -1 (w, Co–O). C38H49N4O7Co (732.8): Calcd. C 62.29,<br />
H 6.74, N 7.65; Found C 62.12, H 6.67, N 7.52. ESI-MS: m/z = 603.5 (C32H46N2O2Co) + ,<br />
183.2 (C6H3N2O5) - .<br />
‐ 70 ‐