X-ray Structure Elucidation of a Pt-Metalloporphyrin and Its Application for Obtaining Sensitive AuNPs-Plasmonic Hybrids Capable of Detecting Triiodide Anions

Abstract

The development of UV–vis spectrophotometric methods based on metalloporphyrins for fast, highly sensitive and selective anion detection, which avoids several of the practical challenges associated with other detection methods, is of tremendous importance in analytical chemistry. In this study, we focused on achieving a selective optical sensor for triiodide ion detection in traces based on a novel hybrid material comprised of Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) and gold nanoparticles (AuNPs). This sensor has high relevance in medical physiological tests. The structure of PtTMeOPP was investigated by single crystal X-ray diffraction in order to understand the metal surroundings and the molecule conformation and to assess if it qualifies as a potential sensitive material. It was proven that the Pt-porphyrin generated 1D H-bond supramolecular chains due to the weak C-H···O intermolecular hydrogen bonding. The presence of ordered voids in the crystal encouraged us to use PtTMeOPP as the sensing material for triiodide ion and to enhance its potential in a novel AuNPs/PtTMeOPP hybrid by the synergistic effects provided by the plasmonic gold nanoparticles. The spectrophotometric sensor is characterized by a detection limit of 1.5 × 10−9 M triiodide ion concentration and a remarkable confidence coefficient of 99.98%.

One A3B Porphyrin Structure—Three Successful Applications

“…From Table 2 it can be noticed that the metal salts NaCl and KI introduce errors in the hydroquinone detection. KI is an avoidable interfering compound, as the average percentage error introduced in the detection process is higher than 16%, as expected from our previous experience [ 71 ].…”

Optical Detection of Bromide Ions Using Pt(II)-5,10,15,20-Tetra-(4-methoxy-phenyl)-porphyrin

“…Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) was obtained as previously reported [20,23] by a metallation reaction of the corresponding porphyrin base using 50% excess of the water-soluble complex PtCl 2 (PhCN) 2 and a large excess (six times more) of CH 3 COONa × 3H 2 O. The purpose of using sodium acetate is to prevent major acidification of the reaction medium and consequently the decomposition of the complex, by capturing the resulting chloride ions.…”

“…In the previous reported studies concerning the use of the same Pt-metalloporphyrin for iodide/bromide [20] or triiodide ion detection [23], the mechanism of detection was different, because in the first case the Pt-metalloporphyrin was incorporated into a PVC membrane and used as a potentiometric sensor, and in the second case it was part of a hybrid material with AuNPs. In the previous reported studies concerning the use of the same Pt-metalloporphyrin for iodide/bromide [20] or triiodide ion detection [23], the mechanism of detection was different, because in the first case the Pt-metalloporphyrin was incorporated into a PVC membrane and used as a potentiometric sensor, and in the second case it was part of a hybrid material with AuNPs.…”

“…10 µg/L/from water No interference from chloride [21] Phenol red spectrophotometry 3.63-19.02 mg kg-1/from capsicum, potatoes and fungi Fast, suitable for routine determinations [22] Our previous experience regarding the detection of bromide ions by means of ion-selective potentiometric sensors, using the Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) as an ionophore, polyvinylchloride (DOP) as a plasticizer, polyvinylchloride (PVC) as a support and tridodeocylmethylammonium chloride (TDMACl) as an additive, provided a detection limit of 8 × 10 −6 M [20]. The changes in optical properties of the AuNPs/PtTMeOPP hybrid material under the influence of triiodide ions were also investigated [23]. It was concluded that the AuNPs/PtTMeOPP hybrid material can optically detect triiodide ions up to a concentration limit of 1.5 × 10 −9 M in media mimicking human physiology.…”

Novel Platinum-Porphyrin as Sensing Compound for Efficient Fluorescent and Electrochemical Detection of H2O2

“…The selectivity of the fluorimetric sensor toward the H2O2 detection is a very important aspect. Taking into consideration that this fluorimetric sensor is destined for medical tests, the interference study, shown in Figure 6, was focused on those anions, cations or compounds that are frequently present in the targeted environments (human serum and urine), such as: glucose (Glu); NaCl; ascorbic acid (AA); phosphate buffer (PSB), AA + NaCl, PSB + NaCl, Glu + NaCl, lactic acid (LA), I2 + LA, potassium dichromate (Cr2O7 2− ), Cr2O7 2− + LA, acetic acid (AcA), potassium permanganate (MnO4 − ), MnO4 − + LA, dilauryl phosphite (LP), LP + NaCl [28,[34][35][36]. The concentration of each potential interfering analyte was 2 × 10 −4 M, 100-fold higher in the mixed solution than that of H2O2 (c = 2 × 10 −6 M).…”