molbank Short Note
Tris(3,7-dihydroxyflavonolate-κO3,O4)chromium(III) 3,O4)chromium(III) Complex Tris(3,7-dihydroxyflavonolate-κO Complex Short Note
Anamaria D. P. P. Alexiou Alexiou 1,1,*, Denny D. E. Silva 11,, Paulete Paulete Romoff Romoff 11 and and Marcelo Marcelo J.J. P. P. Ferreira 22 1
Escola Escolade deEngenharia, Engenharia,Universidade UniversidadePresbiteriana PresbiterianaMackenzie, Mackenzie,Rua Ruada daConsolação Consolação930, 930,São SãoPaulo, Paulo,SP, CEP 01302-907, Brazil;
[email protected] (D.D.E.S.);(D.D.E.S.);
[email protected] (P.R.) SP, CEP 01302-907, Brazil;
[email protected] [email protected] (P.R.) 22 Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, Paulo, SP, CEP Brazil;
[email protected] São Paulo, SP, 05508-090, CEP 05508-090, Brazil;
[email protected] * Correspondence: Correspondence:
[email protected];
[email protected];Tel. Tel.:+55-11-2114-8145 +55-11-2114-8145 Academic Editor: Norbert Haider Received: 19 October 2016; Accepted: 19 January 2016; Published: 22 January 2016
The complex [Cr(3,7diHF) ]·3H 2O (3,7diHF is the of monoanion of flavonoid 3,7complex [Cr(3,7diHF) (3,7diHF is the monoanion flavonoid 3,7-dihydroxyflavone) Abstract: The 3 ]¨ 3H23O dihydroxyflavone) was characterized synthetized and by mass thermogravimetry, spectrometry, thermogravimetry, UVwas synthetized and by characterized mass spectrometry, UV-Vis and FTIR Vis and FTIR spectroscopies. The that datathe indicated that the coordination of the to the spectroscopies. The data indicated coordination of the chromium(III) ionchromium(III) to the flavonoidion increased flavonoid its thermal increased stability. its thermal stability. Keywords: 3,7-dihydroxyflavone; flavonoid; chromium(III)
Introduction 1. Introduction Flavonoids are polyphenolic compounds knownknown for theirfor antioxidant properties. This characteristic Flavonoids are polyphenolic compounds their antioxidant properties. This depends on the presence groups, their ability delocalize characteristic depends on of thehydrogen-/electron-donating presence of hydrogen-/electron-donating groups,totheir ability the to unpaired electron and their potential coordinated [1]. Complexes show delocalize the unpaired electron and to their potential metals to coordinated metals metal-flavonoids [1]. Complexes metalpharmacological properties, such as antitumoral, anticoagulant anti-inflammatory [2] and antioxidant flavonoids show pharmacological properties, such as and antitumoral, anticoagulant and antiactivities [3–8]. [2] In this the synthesis and[3–8]. characterization of athe new complexand containing the flavonoid inflammatory andwork antioxidant activities In this work synthesis characterization of a 3,7-dihydroxyflavone andthe the flavonoid chromium(III) ion is presented. and the chromium(III) ion is presented. new complex containing 3,7-dihydroxyflavone 2. Results Resultsand andDiscussion Discussion 2. + was observed The molecular 809.9 which The molecular ion ion peak peak at at m/z m/z 809.9 which corresponds corresponds to to the the fragment fragment[M´2H] [M−2H]+ was observed in the mass spectrum of the complex [Cr(C H O ) ] (Figure 1). in the mass spectrum of the complex [Cr(C15 15H99O44 )3]3 (Figure 1). Intens. x104
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Figure of the the complex complex[Cr(C [Cr(C15H H9O4)3] in hydroalcoholic solution (90MeOH:10H2O). Figure 1. 1. Mass Mass spectrum spectrum of 15 9 O4 )3 ] in hydroalcoholic solution (90MeOH:10H2 O).
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The thermogravimetric curve of the 3,7-dihydroxyflavone (Figure 2) showed a mass loss of 6.2% The thermogravimetric curve of the 3,7-dihydroxyflavone (Figure 2) showed a mass loss of 6.2% (calculated 6.6%) in the region of 22 to 197 ˝°C due to loss of one water molecule. In the region of 204 ˝°C (calculated 6.6%) in the region of 22 to 197 C due to loss of one water molecule. In the region of 204 C to 355 °C the decomposition process of flavonoid occurred with a mass loss of 87%. Contrarily, the to 355 ˝ C the decomposition process of flavonoid occurred with a mass loss of 87%. Contrarily, the hydration water molecules were lost from the complex between 22 and 366°C (mass loss calculated hydration water molecules were lost from the complex between 22 and 366˝ C (mass loss calculated and observed equal 6.2%). The loss of ligands occurred one by one in three phases: the first one from and observed equal 6.2%). The loss of ligands occurred one by one in three phases: the first one from 366 to 482 ˝°C (mass loss observed 29.4%, calculated 29.2%), and the second one from 482 to 717 ˝°C 366 to 482 C (mass loss observed 29.4%, calculated 29.2%), and the second one from 482 to 717 C (mass loss observed 29.1%). The third dissociation process started at 717 °C, but it apparently only (mass loss observed 29.1%). The third dissociation process started at 717 ˝ C, but it apparently only completed at a temperature higher than 900 ˝°C, therefore outside the measurement region. The data completed at a temperature higher than 900 C, therefore outside the measurement region. The data indicated that the coordination process increased the stability of the flavonoid, as decomposition of indicated that the coordination process increased the stability of the flavonoid, as decomposition of the the complex by ligand loss is only initiated at around 400 °C, whereas the decomposition of free complex by ligand loss is only initiated at around 400 ˝ C, whereas the decomposition of free flavonoid flavonoid is initiated at around 200 °C. is initiated at around 200 ˝ C.
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Temperature ( C) Thermogravimetric curves [Cr(C 3H2O Figure 2. Thermogravimetric curvesof of3,7-dihydroxyflavone 3,7-dihydroxyflavone(a) (a)and andthe thecomplex complex [Cr(C 15H 9O 15 H 9O 4 )43)3]¨]·3H (b) in N2 flow. flow.
The (Figure 3a) 3a) presented presented two two bands bands at The electronic electronic spectrum spectrum of of 3,7-dihydroxyflavone 3,7-dihydroxyflavone (Figure at 341 341 nm nm and and 260 nm assigned respectively to the cinnamoyl system (B + C rings) and benzoyl moiety (A + C ring) 260 nm assigned respectively to the cinnamoyl system (B + C rings) and benzoyl moiety (A + C ring) (band [9]. After (band II) II) [9]. After complexation complexation the the bands bands shifted shifted to to 432 432 and and 291 291 nm nm (Figure (Figure 3b) 3b) indicating indicating that that the the coordination occurs through the 3-hydroxy/4-keto groups, generating a complex with octahedral coordination occurs through the 3-hydroxy/4-keto groups, generating a complex with octahedral geometry (Figure4).4).Similar Similar structures are described the literature band is geometry (Figure structures are described in thein literature [10,11]. [10,11]. AnotherAnother band is observed observed in the complex at 6133c)nm (Figure to3c) attributed to a ligand field transition ofion. the in the complex at 613 nm (Figure attributed a ligand field transition of the chromium(III) ´ 1 chromium(III) ion. The IR spectrum of 3,7-dihydroxyflavone (Figure 5) showed a band at 1627 cm that was 1 in the The IR of 3,7-dihydroxyflavone (Figure 5) showed a´ band at 1627 cm−1indicating that was attributed to spectrum the carbonyl stretching [12]. This band shifted to 1621 cm complex, −1 attributed to the carbonyl This with bandashifted to 1621 cmof the in the complex, indicating that the coordination to thestretching chromium[12]. occurred slight weakening C=O bond. The υ(Cr-O) ´ 1 that the coordination to the chromium occurred with a slight weakening of the C=O bond. The υ(Crat 557 cm confirmed the presence of chromium in the compound. Other bands observed in the IR −1 O) at 557 cm confirmed the presence of chromium spectrum of complex are listed at the end of article. in the compound. Other bands observed in the IR spectrum of complex are listed at the end of article.
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Wavelenght / nm of aofsolution of 3,7-dihydroxyflavone in ethanol (a); a solution of [Cr(3,7Figure 3. 3. UV-Vis UV-Visspectra spectra a solution of 3,7-dihydroxyflavone in ethanol (a); a solution of diHF) 3 ] in dimethyl sulfoxide (b,c). [Cr(3,7-diHF) 3 3 ] in dimethyl sulfoxide (b,c).
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Figure 4. Schematic representation of the complex [Cr(3,7-diHF)333].
3. Experimental 3. ExperimentalSection Section All the and solvents usedused in thisinwork from Aldrich Louis,(Saint MO, All thereagents reagents and solvents this were workpurchased were purchased from(Saint Aldrich USA) similar used without additional Elemental analysis was Louis, or MO, USA)companies or similarand companies and used withoutpurification. additional purification. Elemental performed on a Perkin Elmer CHN 2400 analyzer (Llantrisant, Wales, UK). ESI mass spectrum in the analysis was performed on a Perkin Elmer CHN 2400 analyzer (Llantrisant, Wales, UK). ESI positive mode was obtained on a Bruker Daltonics Esquire 3000 (Bremen, Germany). mass spectrum in the positive mode was obtained on a Bruker Daltonics Esquire 3000 (Bremen, Thermogravimetric analysis were performed with awith TAa TA Instruments TGA Hi-Res Germany). Thermogravimetric analysis were performed Instruments TGA2950 2950 Hi-Res thermogravimetric analyzer (New Castle, DE, USA) using 1–3 mg samples in a ceramic crucible, thermogravimetric analyzer (New Castle, DE, USA) using 1–3 mg samples in a ceramic crucible, −1 −1 −1 −1 ˝ C¨ min 1 . Electronic nitrogen mL·min . ´Electronic absorption spectra in the nitrogen flow flow at at 50 50 mL¨ min´, 1and , andheating heatingrate rateofof1010°C·min absorption spectra in region of 190–1100 nm were recorded on an Agilent 8453 UV-visible spectrophotometer (Shangai, the region of 190–1100 nm were recorded on an Agilent 8453 UV-visible spectrophotometer (Shangai, China), using using aa quartz quartz cuvette cuvette of of optical optical path path length length 1.0 1.0 cm. cm. China),
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Figure 5. Infrared spectra of 3,7-dihydroxyflavone (a) and the complex [Cr(C15H9O4)3] (b). Figure 5. Infrared spectra of 3,7-dihydroxyflavone (a) and the complex [Cr(C15 H9 O4 )3 ] (b). 3,O4)chromium(III) Complex Synthesis 3.1. Tris(3,7-dihydroxyflavonolate-κO Tris(3,7-dihydroxyflavonolate-κO3 ,O4 )chromium(III) Complex Synthesis Seventy-two milliliters of an ethanolic solution containing 0.41 g (1.5 mmol) of 3,7Seventy-two milliliters of an ethanolic solution containing 0.41 g (1.5 mmol) of dihydroxyflavone and 0.21 g (1.5 mmol) of sodium acetate were kept under stirring and reflux for 3,7-dihydroxyflavone and 0.21 g (1.5 mmol) of sodium acetate were kept under stirring and reflux one hour. To this solution, 0.13 g (0.5 mmol) of chromium(III) chloride (CrCl3·6H2O), dissolved in for one hour. To this solution, 0.13 g (0.5 mmol) of chromium(III) chloride (CrCl3 ¨ 6H2 O), dissolved ethanol were added dropwise and the reaction mixture maintained at room temperature for 24 h, in ethanol were added dropwise and the reaction mixture maintained at room temperature for 24 h, when a precipitate appeared, which was filtered, washed with cold ethanol and dried in vacuo (yield: when a precipitate appeared, which was filtered, washed with cold ethanol and dried in vacuo (yield: 39%). Elemental analysis: calcd for C45H33O15Cr ([Cr(C15H9O4)3]·3H2O): C, 62.4; H, 3.84. Found C, 60.6; 39%). Elemental analysis: calcd for C45 H33 O15 Cr ([Cr(C15 H9 O4 )3 ]¨ 3H2 O): C, 62.4; H, 3.84. Found C, H, 3.81. 60.6; H, 3.81. (main bands): 3210(m,br), 3074(vw), 1621(vs), 1589(sh), 1539(vs),1419(vs), 1419(vs),1299(sh), 1299(sh),1205(sh), 1205(sh), FTIR FTIR (main bands): 3210(m,br), 3074(vw), 1621(vs), 1589(sh), 1539(vs), 1182(s), 1147(sh), 1147(sh), 1072(w), 1182(s), 1072(w), 1036(m), 1036(m), 895(m), 895(m), 761(s), 761(s), 693(s), 693(s), 557(m). 557(m).
Acknowledgments: Fundo Mackenzie de Pesquisa.
Acknowledgments: Fundo Mackenzie de Pesquisa.
Author Contributions: Denny D. E. Silva performed the experimental work and all authors designed, wrote and edited the paper. Author Contributions: Denny D. E. Silva performed the experimental work and all authors designed, wrote and edited the paper. Conflicts of Interest: The authors declare no conflict of interest.
Conflicts of Interest: The authors declare no conflict of interest.
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