We present here a facile method for nonaqueous synthesis of highly crystalline nitrogen-doped carbon dots (N-CDs) via oligomerization of ethylene glycol while heating with βalanine at 170 °C for 30 min. It exhibited bright bluish photoluminescence (PL) at λ emission = 461 nm, corresponding to a relative PL quantum yield of 14.3% and an average PL lifetime of 7.4 ns. High-resolution transmission electron microscopy of N-CDs revealed systematically self-assembled transverse oligomeric chains of ethylene glycol doped with β-alanine to form hexagonal symmetry, and their crystalline nature was revealed from electron diffraction measurement. The structure and composition of N-CDs are deduced from 13 C nuclear magnetic resonance, highresolution mass spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy measurements, which collectively suggested oligomerization of β-alanine-doped ethylene glycol. The N-CDs are then demonstrated as an efficient probe for quantitative detection of Cr(VI) species at different pHs and 4-nitrophenol (4-NP) via PL quenching. The limits of detection (LoD) are deduced from respective linear Stern−Volmer plots, e.g., 1.1 μM for H 2 CrO 4 (at pH 0.9), 2.5 μM for HCrO 4 − (at pH 3.5), and 0.29 μM for CrO 4 2− (at pH 9.0). The detection of Cr(VI) is highly selective against several cationic (e.g.

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