Polyhydroquinoline nanoaggregates: A dual fluorescent probe for detection of 2,4,6-trinitrophenol and chromium (VI)

Highlights

• Fluorescent nanoaggregates of polyhydroquinoline derivative were fabricated in 95% aqueous DMF medium.

• The nanoaggregates afforded TNP and Cr (VI) detection in 95% aqueous medium.

• The chemosensor was been synthesized through one-pot route without tedious work-ups.

• The so developed chemosensors enabled highly selective detection of TNP and Cr (VI) in real samples.

Abstract

Fluorescent polyhydroquinoline (PHQ) derivative was fabricated utilizing one-pot engineered course. The PHQ derivative indicated aggregation induced emission enhancement (AIEE) with arrangement of nanoaggregates of size 11–13 nm in 95% watery DMF medium. The fluorescence emission of PHQ nanoaggregates was extinguished by including TNP and Cr (VI). They indicated prevalent fluorescence quenching towards both TNP and Cr (VI) over other meddling nitro-compounds and metal particles. In light of results got we presumed that both photo-induced fluorescence quenching of PHQ nanoaggregates by TNP, while Inner Filter Effect (IFE) was in charge of fluorescence quenching of PHQ nanoaggregates by Cr (VI). The PHQ nanoaggregates empowered identification of TNP and Cr (VI) down to 0.66 μM (TNP) and 0.28 μM (Cr (VI)). The use of PHQ nanoaggregates were reached out for location of TNP and Cr (VI) in genuine water tests.

Introduction

Ecological security concerns have arrived at alarmingly abnormal states inferable from nonstop unreasonable human exercises. The unregulated use and disposal of hazardous compounds have brought about negative impacts on the earth. Substantial metal particles and nitroaromatic compounds (NACs) fall into the classification of hazardous compounds that posture potential danger to human wellbeing and environment [1]. NACs, for example, trinitrotoluene (TNT), 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (2,4-DNT), 2,4-dinitrophenol (2,4-DNP), 4-nitrotoluene (4-NT), nitrobenzene (NB), and so on are arranged under mixes with prospective danger of fear based oppression and natural security in various nations [2]. Among different NACs, TNP otherwise called picric acid, is viewed as the most threatening as it shows high explosive velocity [3] and low wellbeing coefficient [4]. Likewise, TNP has higher water dissolvability than TNT [5], along these lines genuinely contaminating ground water, soil and air [1]. TNP is broadly utilized in rocket powers, firecrackers, dyes [6], matches, pharmaceutical, and leather businesses [2]. The persistent ingestion of TNP may cause skin/eye bothering, sickness, dazedness, spewing, and stomach torment [4,7]. There are reports where TNP has been utilized by terrorist groups for blasts in several areas [8].

Then again, chromium (VI) is a famous lethal substantial metal that aggravates the biological system [9]. Among the two watery stable conditions of chromium, Cr (III) and Cr (VI), Cr (VI) is known to have cancer-causing nature and mutagenicity towards living life forms [10]. It is broadly utilized in metallurgy, leather tanning, dying and catalysis industry [11]. The most extreme degree of Cr (VI) in drinking water, allowable by World Health Organization is 1 μM [12]. In any case, shockingly because of unregulated mechanical waste release into the inland surface water, the substantial metal contamination is viewed as genuine risk in numerous pieces of world, particularly the developing nations [13]. Globally the defilement of drinking water supply by Cr (VI) is of extraordinary concern [14]. Ingestion of Cr (VI) polluted water can cause queasiness, liver and kidney harm [15] and hemolysis [16].

There are different very much established scientific procedures for location of Cr (VI) that includes electrochemistry [17], atomic absorption spectroscopy [18], inductively coupled plasma mass spectrum (ICP-MS) [19,20], and high performance liquid chromatography (HPLC) [21,22]. Similarly numerous analytical methods have been reported for monitoring TNP content in common matrix, including ion chromatography [23], electrochemical techniques [23,24], ion-mobility spectrometry [25], Raman spectroscopy [26], and so forth have been reported. Despite the fact that these strategies offer high affectability however experience the ill effects of complicated instrumentation, tedious and advanced pretreatment, subsequently restricting their utilization for on location identification [27,28]. Among every one of these strategies the fluorescence based chemosensors are the one that have advanced a ton inferable from on location appropriateness, high affectability, cost viability and accessible instrument prerequisite [10,29]. Considering the advantages of fluorescent-based touchy sensors, a marketed sensor FidoXT have been made [30]. It involves amplifying fluorescence polymers that empowered location of military-grade mixes utilized in hand crafted explosives and IED's, incorporating PETN in parts per quadrillion (ppq) [31,32]. There are different fluorescent based sensors like nanosheets [33,34], nanoaggregates [35], conjugated polymers [36], quantum dots[37], carbon dots [38], metal organic frameworks [39,40] answered to identify and measure different metal particles and NACs. There are various fluorescent sensors that permit location of metal particles or NACs in non-aqueous medium; anyway their appropriateness is interfered with when connected in watery medium [41]. This is on the grounds that most fluorescent mixes show aggregation caused quenching (ACQ) in aqueous medium. It's a phenomenon wherein a fluorophore show debilitated fluorescence in aqueous medium attributable to solid collection actuated π-π stacking by hydrophobic aromatic backbone [35]. Over the previous decades there are rich reports of accumulation induced emission (AIE) or aggregation induced emission enhancement (AIEE) materials, which demonstrate no or frail fluorescence in arrangement yet show solid luminescence in the aggregated state [42]. Organic molecules such as pentacenequinone [43], naphthalimide [44], α-cyanostilbene [42], tetraphenylethylene [45], siloles, arylethene derivatives that emit strongly in their aggregated or solid state have been reported [43].

In this, we have synthesized a polyhydroquinoline subordinate by an effortless one-pot course which framed fluorescent nanoaggregates in blended fluid media. Polyhyroquinoline are significant structural motif in view of biological as well as medicinal applications. It acts like donor-acceptor framework where the heading of charge movement is from the benzene ring towards the quinoline ring [46]. As far as we could possibly know it's the primary report where fluorescent nanoaggregates of polyhydroquinolines are utilized for double identification of Cr (VI) and TNP.