Sintesis Turunan Pirazola dari Kurkumin Hasil Isolasi Bubuk Kunyit Aceh dan Uji Aktivitasnya sebagai Kemosensor Fluoresens Ion Timbal (II)

Vina Aida Roza, Prof. Dra. Tutik Dwi Wahyuningsih, M.Si., Ph.D.; Prof. Indriana Kartini, S.Si., M.Si., Ph.D.

2023 | Skripsi | KIMIA

             Telah dilakukan penelitian tentang aktivitas kemosensor berfluoresensi pirazola turunan dari kurkumin terhadap logam Pb²⁺. Penelitian ini bertujuan untuk mengisolasi kurkumin dari bubuk kunyit Aceh, melakukan sintesis turunan pirazola dari kurkumin, dan mengevaluasi aktivitas serta selektivitasnya sebagai kemosensor kation logam Pb²⁺.

            Penelitian ini diawali dengan melakukan ekstraksi kunyit melalui metode maserasi dengan pelarut etil asetat, hasil ekstraksi didefatisasi dengan petroleum eter dan direkristalisasi menggunakan isopropil alkohol sehingga diperoleh kurkumin dengan kemurnian tinggi. Selanjutnya, kurkumin hasil isolasi direaksikan dengan 2-hidrazinopiridin menggunakan katalis asam asetat dan direfluks selama 6 jam untuk menghasilkan pirazola kurkumin. Elusidasi struktur terhadap produk hasil sintesis dilakukan dengan spektrometer FTIR, ¹H-NMR dan ¹³C-NMR. Produk hasil sintesis diuji kemampuan kemosesor fluoresensnya terhadap logam Pb²⁺ dengan menentukan LOD, LOQ, quantum yield dan interferensinya.

            Hasil isolasi menghasilkan kurkumin berupa padatan kuning oranye dengan rendemen 1,78?n kemurnian 96,2%. Reaksi siklokondensasi menghasilkan pirazola kurkumin berupa padatan hijau kekuningan dengan rendemen 98,18?n titik leleh 101,1­–103,4 ?. Uji aktivitas kemosensor terhadap senyawa pirazola kurkumin menghasilkan sistem deteksi turn-on pada logam Pb²⁺ dengan nilai LOD dan LOQ sebesar 0,3 µM dan 0,91 µM. Selain itu, diperoleh nilai quantum yield yang kecil yaitu 0,057 dan interferensi yang cukup signifikan sehingga membuat pirazola kurkumin kurang selektif terhadap logam Pb²⁺.

            A research study was conducted to investigate the fluorescing chemosensor activity of pyrazole derived from curcumin on Pb²⁺ ions. This study aims to extract curcumin from Aceh turmeric powder, synthesize pyrazole derivatives of curcumin, and evaluate its activity and selectivity as a chemosensor for Pb²⁺ ions.

            This research was initiated by extracting turmeric powder using the maceration method with ethyl acetate, the extraction results were defatted using petroleum ether and recrystallized with isopropyl alcohol to obtain highly pure curcumin.  Next, the isolated curcumin was reacted under reflux for 6 h with 2-hydrazinopyridine in the presence of acetic acid catalyst to yield pyrazoles.  The structure of the synthesized product was analyzed using FTIR, ¹H-NMR, and ¹³C-NMR spectrometers. The synthesized products were further evaluated as chemosensors for Pb²⁺ metal ions by determining their limits of detection (LOD), limits of quantification (LOQ), quantum yield, and interferences.

            The result showed that curcumin was obtained as a yellow-orange solid with a yield of 1.78% and a purity of 96.2%. The cyclocondensation reaction produced pyrazole curcumin in the form of a yellowish-green solid with a yield of 98.18% and m.p. of 101.1–103.4 ?. Chemosensor activity test on pyrazole curcumin resulted in a turn-on detection system for Pb²⁺ metal with LOD and LOQ values of 0.30 µM and 0.91 µM. Additionally, the quantum yield value was relatively low at 0.057, and significant interference was observed, indicating that pyrazole curcumin displayed limited selectivity for Pb²⁺ metal ions.

Kata Kunci : fluoresensi, kemosensor, kurkumin, pirazola, rekristalisasi