HIGH SENSITIVITY VAPOUR RECOGNITION AND MONITORING USING PORPHYRIN-CALIXARENE FILMS FOR A WIDE RANGE OF ANALYTES

识别和测量存在于或进入大气中的污染物或污染物蒸气从未像今天这样重要。目前对我们环境的兴趣源于大量科学数据证实了全球变暖和相关的气候变化。此外，恐怖主义所造成的威胁，即有毒气体被非法引入我们的空气供应，突出了对高度响应的传感材料的迫切需求，这些材料可以形成有效传感系统中的活性成分。许多监测设备利用基于电容器的或电化学传感元件，但这些通常是非特异性的，并且通常需要高的操作温度。有机材料以电子鼻的形式最引人注目，其中导电聚合物充当化学电阻器。然而，这些聚合物的性能逐批再现的问题阻碍了它们的商业开发。我们以前的研究已经产生了一个家族的卟啉，其表现出有用的传感材料的大部分特性，用于广泛的分析物和低浓度（通常在0.5 /10 ppm的区域）的应用。卟啉是一种高度共轭的有机分子，具有丰富的紫外-可见吸收光谱。这些转变很容易被各种各样的气态分析物分子的吸附所改变。对吸收光谱的仔细研究表明，蒸气暴露导致的详细变化因分析物而异。目前，先进的、高分辨率的、便携式的，最重要的是，廉价的（<2- 3 k）紫外可见光谱仪的可用性意味着，即使是由与不同分析物的相互作用引起的修正光谱中的非常小的变化也可以被容易地检测到。因此，通过在阵列配置中使用感测材料家族的几个成员，可以期望识别和量化特定分析物的浓度。我们的卟啉可加工成Langmuir-Schaeffer（LS）膜，尽管我们的工作已经表明，使用主体组分/例如脂肪酸或杯[n]芳烃酸/有助于膜形成并导致样品的高再现性。在这个拟议的研究计划中，我们希望开发一个家庭的卟啉（calixporphs），其中卟啉单体接枝周围的杯[n]芳烃羧酸环的边缘，形成一个分子拥有的蒸汽/敏感功能的卟啉耦合到极好的成膜性能的杯[n]芳烃酸物种。此外，与熔点通常在250 /300 ° C范围内的许多其他主体材料相比，已知杯[n]芳烃是相对热稳定的化合物。重要的是，我们希望调用杯[n]芳烃本身的相互作用性质，已知其以加合物的光学性质在UV-可见光区域中显著改变的方式结合广泛的小分子如NO2、甲苯和各种金属离子。该计划的主要目的是实现一种分子系统，其中所得到的薄膜的光学性质受到分析物和卟啉部分和/或杯[n]芳烃腔之间存在相互作用的显着影响。这些分子的双功能性有望提高选择性，超越我们目前的成就，并导致非常有用的传感材料。杯芳烃载体的多功能特性（结合能力、孔隙率、成膜能力、热稳定性）与卟啉的蒸气敏感性相结合，使我们能够开发出响应速度快、灵敏度高、识别能力高（选择性/使用阵列）的传感材料，并且最有可能的是显示出抑制的温度依赖性的材料。

The identification and measurement of pollutant or contaminant vapours present in or entering the atmosphere has never been more important than today. Current interest in our environment has resulted from overwhelming scientific data confirming global warming and associated climate change. Furthermore, the threat posed by terrorism of toxic vapours introduced criminally into our air supply highlights the urgent need for highly responsive sensing materials that can form the active ingredients in efficient sensing systems. Many monitoring devices utilise semiconductor-based or electrochemical sensing elements but these are often non-specific and usually require high operating temperatures. Organic materials have most notably attracted attention in the form of the electronic nose in which conducting polymers act as chemi-resistors. However, problems with reproducing the behaviour of these polymers from batch to batch have hindered their commercial development. Our previous research has produced a family of porphyrins which exhibits most of the characteristics of useful sensing materials for application with a wide range of analytes and at low concentrations (typically in the region 0.5 / 10ppm). Porphyrins are highly conjugated organic molecules which display a rich UV-visible absorption spectrum . These transitions are readily modified by the adsorption of a wide range of gaseous analyte molecules. Close study of the absorption spectrum shows that the detailed changes resulting from vapour exposure are different from analyte to analyte. The current availability of sophisticated, high resolution, portable and, most importantly, inexpensive (<2-3k) UV-visible spectrophotometers now means that even very small variations in the modified spectra arising from interactions with different analytes can be detected easily. Thus, by using several members of a family of sensing materials in an array configuration, one can expect to identify and quantify the concentration of a particular analyte. Our porphyrins are processable as Langmuir-Schaeffer (LS) films although our work has shown that the use of a host component / for example, a fatty acid or a calix[n]arene acid / aids film formation and leads to high reproducibility of samples. In this proposed research programme, we wish to develop a family of porphyrins ( calixporphs ) in which the porphyrin monomer is grafted around the edge of a calix[n]arene carboxylic acid ring to form a molecule possessing the vapour /sensitive functionality of the porphyrin coupled to the superb film-forming properties of the calix[n]arene acid species. Furthermore, calix[n]arenes are known to be relatively thermally stable compounds compared to many other host materials with melting points usually in the range 250 / 300oC. Importantly, we wish to invoke the interaction properties of calix[n]arenes themselves which are known to bind a wide range of small molecules such as NO2, toluene and various metal ions in such a way that the optical properties of the adduct are significantly modified in the UV-visible region. The principal aim of this programme is to realise a molecular system in which the optical properties of resulting thin films are affected dramatically by the presence of interactions between the analyte and the porphyrin moieties and / or the calix[n]arene cavities. The bifunctionality of these molecules would be expected to enhance selectivity beyond our present achievements and lead to extremely useful sensing materials. The versatile properties of the calixarene carrier (binding ability, porosity, film-forming ability, thermal stability) coupled to the vapour sensitivity of the porphyrins should allow us to develop sensing materials displaying fast response rate, high sensitivity, high identification power (selectivity / with the use of arrays) and most probably materials showing suppressed temperature dependence.