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Chromone hydrazone ligand namely AFCTSC was synthesised and fully characterised using spectroscopy method of FT-IR, UV-Vis, 13C & ¹H NMR. The fluorescence emission of free AFCTSC ligand was observed to be weak at 460 nm. The ligand showed high selectivity to Zn2+ by giving remarkable red shift of the emission to 505 nm, while other metal ions such as Ca2+, Co2+, Cu2+, Fe2+, Mn2+ and Ni2+ quenched the fluorescence intensity of the ligand. Furthermore, Zn2+ addition into AFCTSC solution caused fluorescent colour change from blue to green when the solution is illuminated with a UV lamp (λ=365nm). The limit of detection obtained was 4.5×10-7 M making AFCTSC a promising fluorescent probe that could be an alternative to existing analytical methods for determination of Zn2+. The binding study revealed each molecule of AFCTSC was coordinated to Zn2+ in mononegative tridentate manner via ONS donor atoms. [ABSTRACT FROM AUTHOR]

Students' mastery of the Three Representation Levels of Chemistry Concept (macroscopic, microscopic, and symbolic) is still weak and this has affected their academic performance in Chemistry subject. This has resulted from the poor engagement of students in the teaching and learning process. The current teaching practice is teachercentered learning and does not encourage self-directed learning. Therefore, there is a need to implement Blended Problem-Based Learning (BPBL) which encourages students’ self-directed learning in face-to-face and online learning mode. This study is aimed at: (i) identifying how self-directed learning skills are being applied in the BPBL, and (ii) identifying how BPBL enhances Chemistry learning. This study employed a qualitative approach through a case study research design (exploratory and explanatory). Two teachers and 20 students were selected using purposive sampling, which became the sample for this study. Data were collected from observations, students’ documents, and semi-structured interviews and analysed thematically. Generally, the findings indicated that the BPBL approach was able to enhance students’ ability to: (i) plan a problem-solving process, (ii) analyze, assess understanding and provide justification as well as (iii) evaluate references and information. These skills have contributed to mastery of the Three Representation Levels of Chemistry Concept and they were able to avoid the formation of alternative concepts. The findings of this study can serve as a reference to effectively implement BPBL in the context of Chemistry learning in Malaysia. [ABSTRACT FROM AUTHOR]