Zinc titanate nanopowder: an advanced nanotechnology based recyclable heterogeneous catalyst for the one-pot selective synthesis of self-aggregated low-molecular mass acceptor–donor–acceptor–acceptor systems and acceptor–donor–acceptor triads
作者:Paramita Das、Ray J. Butcher、Chhanda Mukhopadhyay
DOI:10.1039/c2gc16641k
日期:——
Highly stable, environmentally benign ZnTiO3 nanopowder has been prepared via a sustainable solâgel method. The nanopowder (90 nm) has been thoroughly characterized by SEM, XRD, EDS, Laser Raman, photoluminescence, UV and IR. The activity of the catalyst was probed through one-pot four-component reaction of aldehydes, ketones and two equivalent propanedinitriles in water without requiring any additives or anhydrous conditions. The reaction requires two different catalytic functions, i.e., an acidic one which is given by Ti(IV) ions and a basic one, given by the oxide ion incorporated within the ZnTiO3 metal oxide framework. The advantages of this method lie in its simplicity, cost effectiveness, environmental friendliness, and easier scaling up for large scale synthesis without using high pressure, temperature and toxic chemicals. As water was used as a reaction medium and since we are particularly interested in the isolation of a non-aromatic intermediate, the elimination of poisonous HCN was prevented by the Lewis acid character of Ti4+ up to a sufficiently high temperature. Thus, this process can be considered as a âgreenâ process. Elimination of HCN at higher temperatures still maintains âgreenâ attributes as HCN can be trapped by the basic catalyst under such conditions. Spontaneous generation of low molecular mass self-aggregated organic materials, their one-dimensional packing, and interesting photophysical properties are reported.
通过可持续的溶胶-凝胶法制备了高度稳定、环境友好的ZnTiO3纳米粉末。通过SEM、XRD、EDS、激光拉曼、光致发光、UV和IR对纳米粉末(90 nm)进行了全面的表征。通过在水中的醛、酮和等量的丙二腈的四组分一步反应探究了催化剂的活性,无需任何添加剂或无水条件。该反应需要两种不同的催化功能,即Ti(IV)离子提供的酸性功能和ZnTiO3金属氧化物框架中包含的氧化离子提供的基本功能。该方法的优势在于其简单性、成本效益、环境友好性,以及无需高压、高温和有毒化学品即可更容易地扩大规模进行大规模合成。由于使用水作为反应介质,并且我们特别关注非芳香性中间体的分离,因此在足够高的温度下,Ti4+的Lewis酸性质防止了有毒HCN的消除。因此,该过程可以被视为一种“绿色”过程。在更高温度下消除HCN仍然保持“绿色”特性,因为在这种条件下HCN可以通过碱性催化剂捕获。报道了低分子量自聚集有机材料的自发生成、它们的一维堆积以及有趣的光物理性质。