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

识别和测量大气中存在或进入大气的污染物或污染物蒸气从未像今天这样重要。目前人们对环境的关注源于大量的科学数据证实了全球变暖和相关的气候变化。此外，恐怖主义对犯罪分子将有毒蒸汽引入我们的空气供应所构成的威胁突出了对高响应传感材料的迫切需要，这些材料可以形成有效传感系统的有效成分。许多监测设备利用半导体或电化学传感元件，但这些通常是非特异性的，通常需要较高的工作温度。有机材料以电子鼻的形式引起了人们的注意，其中导电聚合物充当化学电阻。然而，这些聚合物在批次之间的行为再现问题阻碍了它们的商业发展。我们之前的研究已经产生了一个卟啉家族，它展示了有用的传感材料的大多数特性，适用于各种分析物和低浓度（通常在0.5 / 10ppm区域）。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。这些转变很容易被广泛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，蒸汽暴露引起的详细变化因分析物而异。目前，复杂、高分辨率、便携、最重要的是价格低廉（<2-3k）的紫外可见分光光度计的可用性意味着，即使是与不同分析物相互作用引起的修改光谱中的非常小的变化，也可以很容易地检测到。因此，通过在阵列配置中使用传感材料家族的几个成员，人们可以期望识别和量化特定分析物的浓度。我们的卟啉可以加工成Langmuir-Schaeffer （LS）薄膜，尽管我们的工作表明，使用宿主成分（例如脂肪酸或杯[n]芳烃酸）有助于薄膜的形成，并导致样品的高再现性。在这个提议的研究计划中，我们希望开发一个卟啉家族（calixporphs），其中卟啉单体被接枝在杯[n]芳烃羧酸环的边缘，形成一个具有卟啉的蒸汽/敏感功能的分子，并与杯[n]芳烃酸物种具有极好的成膜特性。此外，与许多其他主体材料相比，杯[n]芳烃是相对热稳定的化合物，熔点通常在250 / 300℃范围内。重要的是，我们希望调用杯[n]芳烃本身的相互作用性质，已知杯[n]芳烃可以结合广泛的小分子，如NO2，甲苯和各种金属离子，从而使加合物的光学性质在紫外可见区域得到显着改变。该计划的主要目的是实现一个分子系统，在该系统中，分析物与卟啉部分和/或杯[n]芳烃空腔之间的相互作用极大地影响了所得到薄膜的光学性质。这些分子的双功能有望提高选择性，超越我们目前的成就，并导致非常有用的传感材料。杯芳烃载体的多用途特性（结合能力、孔隙度、成膜能力、热稳定性）与卟啉的气敏性相结合，将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，并且很可能显示出抑制温度依赖性的材料。

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.