Siti Marfuah

Bio: Siti Marfuah is an academic researcher from State University of Malang. The author has contributed to research in topic(s): Xanthene & Antibacterial activity. The author has an hindex of 5, co-authored 28 publication(s) receiving 124 citation(s). Previous affiliations of Siti Marfuah include State University of Semarang.

Syntheses, structures and vibrational spectroscopy of some 1:1 and 1:2 adducts of silver(I) oxyanion salts with 2,2'-bis(pyridine) chelates

Abstract: Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of 1:1 stoichiometry of silver(I) oxyanion salts (perchlorate, nitrate, trifluoroacetate (‘tfa’) (increasing basicity)) with 2,2′-bis(pyridine) ligands (2,2′-bipyridyl, ‘bpy’; 2,2′-biquinolyl, ‘bq’; 2,2′-dipyridylketone, ‘dpk’; 2,9-dimethylphenanthroline, ‘dmp’). The adducts take two forms: (a) neutral mononuclear molecules, in which the 2,2′-bis(pyridine) ligand behaves as a chelate, with the silver coordination number dependent on the denticity of the anion; these are Agtfa:bpy (1:1) and AgClO4:bq (1:1) (and various (ionic) acetonitrile or pyridine solvates AgClO4:bq/dmp:MeCN/py (1:1:1), in which the solvent molecules are coordinated); and (b) one-dimensional polymers. The latter are diverse: in AgClO4:bpy, dpk (1:1), the anion is discrete, the polymer made up of an array of two-coordinate silver atoms linked by bpy ligands twisted about their central connecting element. In AgNO3:bpy, bq (1:1), the bpy ligands are chelating with the oxyanions bridging, cf. previously reported AgNO3:dpk (1:1), in which the nitrate chelates the metal, with the dpk bridging, chelating N,O to one silver, while the other nitrogen bridges to the next. With Agtfa, a novel binuclear adduct has been isolated in conjunction with the hydrated ligand, Agtfa:dpk:(dpk · H2O) (1:1:2). The far-IR spectra of several of these complexes show bands that can be assigned to the ν(AgN) modes, the positions of these bands correlating well with the relative Ag–N bond lengths. Syntheses and single-crystal X-ray structural characterizations are also reported for various adducts of silver(I) perchlorate, nitrate and trifluoromethanesulfonate with bpy, bq, ‘phen’ (= 1,10-phenanthroline), and ‘dmp’, of stoichiometry AgX:L (1:2). In each case the complex is ionic [AgL2]X; the silver atom is four-coordinate, but diverse and remarkable variations in stereochemistries associated with changes in the interligand N–Ag–N angles, presumably influenced by the different packing arrangements, are observed.

The influence of assignment methods on the development aspects of religious and moral values of early childhood during the covid-19 pandemic

Abstract: The covid-19 pandemic period has not yet passed. Learning activities are carried out online or through distance learning. Distance learning requires teachers to assign tasks to children to keep learning from home every day. This research aims to see how assignment approaches affect the development of religious and moral values in early childhood in IT ADAR PAUD institutions during the Covid-19 pandemic. This study examines the significance test between the independent variables of the assignment system and the dependent variable of early childhood religious and moral values using quantitative correlation research of product-moment through the t-test. The significance value of 0.753 is greater than 0.05, as shown by the t-test. As a result, it can be inferred that the assignment process has an effect on facets of religious and moral values formation in early childhood during the Covid-19 pandemic period. It is expected that educators in the pandemic period will continue to use the assignment method to ensure that facets of children's religious and moral beliefs evolve with time.

Pengaruh praktikum dan demonstrasi dalam pembelajaran inkuiri terbimbing terhadap motivasi belajar siswa pada materi asam basa ditinjau dari kemampuan awal

Abstract: This study aimed to compare the students' motivation that learned by two different methods viewed from prior knowledge. This study used the quasi-experimental design. Data were obtained from motivation questionnaire which consist of 31 point statements. Data were analyzed using two ways ANOVA. The results showed that: (1) there was differences in students' motivation that learned with hands-on and demonstration in guided inquiry learning, (2) student with high prior knowledge have better motivation in learning rather than students with low prior knowledge, (3) there was no interaction between learning methods and prior knowledge on students' motivation. Penelitian ini bertujuan untuk mengetahui perbedaan motivasi belajar siswa yang dibelajarkan dengan 2 metode berbeda ditinjau dari kemampuan awal. Penelitian ini menggunakan rancangan eksperimen semu. Data penelitian diperoleh dari angket motivasi yang terdiri atas 31 butir pernyataan. Data dianalisis menggunakan ANOVA dua jalan. Hasil penelitian menunjukkan bahwa: (1) ada perbedaan motivasi belajar siswa yang dibelajarkan dengan praktikum dan demonstrasi dalam pembelajaran inkuiri terbimbing, (2) siswa dengan kemampuan awal tinggi memiliki motivasi belajar yang lebih baik dibandingkan siswa dengan kemampuan awal rendah, (3) tidak ada interaksi antara metode pembelajaran dan kemampuan awal terhadap motivasi belajar siswa.

Pengaruh Bahan Ajar Multimedia Terhadap Hasil Belajar Dan Persepsi Mahasiswa Pada Matakuliah Kimia Organik I

Abstract: Penelitian ini bertujuan untuk mengetahui pengaruh bahan ajar multimedia terhadap hasil belajar dan persepsi mahasiswa pada matakuliah kimia organik I. Sebanyak 31 mahasiswa sebagai sampel diberikan pretes dan postes, serta angket untuk mengetahui reaksi mereka terhadap bahan ajar multimedia. Hasil yang diperoleh sangat positif dengan menghasilkan peningkatan terhadap hasil belajar. Mahasiswa merasa senang, termotivasi, dan tertarik untuk belajar kimia organik I dengan bahan ajar multimedia. Mahasiswa berharap pembelajaran lainnya bisa menggunakan multimedia. This study aimed to investigate the effect of multimedia teaching materials to students’ learning outcomes and perceptions in organic chemistry I courses. There were 31 university students as a sample that given pre-and posttest, and a survey to ascertain their reactions toward the multimedia teching material. The results obtained were very positive with an increase to the learning outcomes. Students felt happy, motivated, interested in learning organic chemistry I with multimedia teaching material. Students expected that the other learning could used multimedia.

Synthesis of Fe3O4 Nanoparticles using PEG Template by Electrochemical Method

Abstract: One of the nanoparticles which have been developed is magnetite. Due to its magnetism and reactivity, this particle can be used in various fields including technology, environment, and biomedical. One simple method to synthesize magnetite is electro-oxidation of iron in the water. The particle size produced by this method can be adjusted by controlling the electrochemical cell parameters. Unfortunately, this method usually releases polydispersed particles. One solution to overcome this problem is by using an in situ PEG in the synthesis process. In this research, PEG 6000 was chosen as a template, so the synthesis process was performed by electro-oxidation of iron in the dilute solution of PEG. Particles with an average diameter of 62.5 nm were obtained. The monodispersity, surface area, and crystallinity of the particles increased in this way. The specific surface area increased from 55.322 to 391.314 m2/g. The results of XRD and FTIR analysis showed that PEG acted as a template in the synthesis process. In addition, the yield obtained with PEG template was larger than without the template. This method is quite promising as a way of synthesis of magnetite nanoparticles.

Square planar silver(I) complexes: A rare but increasingly observed stereochemistry for silver(I)

Abstract: The square planar Ag(I) stereochemistry is generally acknowledged as rare, with only ∼2% of all reported silver complexes possessing this stereochemistry. Many researchers reporting such complexes often mistakenly believe that their example is one of only a handful of previously reported examples. This is despite the fact that there are currently around 65 well characterised complexes containing square planar Ag(I) ions, about half of which are coordination polymers. In this review, we critically examine each example and draw attention to trends that arise in their formation. The scope is limited to ‘traditional’ coordination complexes. Inorganic complexes containing extended mineral like structures, and complexes containing silver-π or silver-arene motifs are not considered in this review.

A Series of Ca(II) or Ba(II) Inorganic–Organic Hybrid Frameworks Based on Aromatic Polycarboxylate Ligands with the Inorganic M–O–M (M = Ca, Ba) Connectivity from 1D to 3D

Abstract: Solvothermal reactions of Ca(NO3)2 or Ba(NO3)2 with aromatic carboxylate ligands afforded four new inorganic–organic hybrid frameworks, [Ca(PBDC)(H2O)3]n (1), [Ca(OBDC)(H2O)]n (2), [Ba5(OBDC)4(H2O)2(NO3)2]n (3), and [Ba3(BTC)2(H2O)4]n (4) (H2PBDC = terephthalic acid, H2OBDC = phthalic acid, H3BTC = 1,3,5-benzenetricarboxylic acid). These compounds have been fully characterized by single crystal X-ray diffraction, powder X-ray diffraction, satisfactory elemental analysis, IR spectra, and TG analysis. X-ray analysis shows that compound 1 features a one-dimensional chain (1D) structure with the I1O0 connectivity, both compound 2 and compound 3 feature a two-dimensional (2D) layer structure with the I1O1 connectivity, I2O0 connectivity, respectively, compound 4 features a three-dimensional (3D) framework with a rare I3O0 connectivity. Thermal stabilities and luminescent properties of compounds 1–4 and NLO property of compound 4 have also been investigated.

Synthesis, antimicrobial and antiproliferative activity of novel silver(I) tris(pyrazolyl)methanesulfonate and 1,3,5-triaza-7-phosphadamantane complexes.

Abstract: Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)(PPh3)] (2), [Ag(Tpms)(PCy3)] (3), [Ag(PTA)][BF4] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh3 = triphenylphosphane, PCy3 = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane} have been synthesized and fully characterized by elemental analyses, 1H, 13C, and 31P NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N3-facially coordinating mode, while in 2 and 5 a N2O-coordination is found, with the SO3 group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activi...

Anion-dependent self-assembly of silver(I) and diaminotriazines to coordination polymers: non-covalent bonds and role interchange between silver and hydrogen bonds.

Abstract: New coordination polymers have been obtained by the self-assembly of silver salts AgX (X = BF4, PF6, CF3SO3) and 2,4-diamino-6-R-1,3,5-triazines L (R = phenyl and p-tolyl) of formulas AgLX (1−6). A complex of different stoichiometry, [Ag3L2(H2O)(acetone)2](BF4)3, 7 (R = phenyl), has also been synthesized. The three-dimensional structures of five compounds have been determined by X-ray diffraction studies. For the AgLX complexes, when X = BF4 and R = phenyl or p-tolyl, chiral chains with alternating Ag and L are formed. The chains are cross-linked by the counteranions in a three-dimensional fashion through hydrogen bonds and weak Ag···F interactions giving rise to a structure with solvent-filled channels. Different and more compact structures have been found when the counteranion is CF3SO3 (OTf). When R = phenyl, sheets are formed which consist of [Ag2(OTf)2L2] units with double triflate bridges and which contain columns of π−π stacked arenes. Hydrogen bonds connect the sheets. When AgOTf is used and R is ...