Vibrational spectroscopic characterization of the phosphate mineral kulanite Ba(Fe(2+),Mn(2+),Mg)2(Al,Fe(3+))2(PO4)3(OH)3.
The mineral kulanite BaFe2Al2(PO4)3(OH)3, a barium iron aluminum phosphate, has been studied by using a combination of electron microscopy and vibrational spectroscopy. Scanning electron microscopy with EDX shows the mineral is homogenous with no other phases present. The Raman spectrum is dominated by an intense band at 1022cm(-1) assigned to the PO4(3-)ν1 symmetric stretching mode. Low intensity Raman bands at 1076, 1110, 1146, 1182cm(-1) are attributed to the PO4(3-)ν3 antisymmetric stretching vibrations. The infrared spectrum shows a complex spectral profile with overlapping bands. Multiple phosphate bending vibrations supports the concept of a reduction in symmetry of the phosphate anion. Raman spectrum at 3211, 3513 and 3533cm(-1) are assigned to the stretching vibrations of the OH units. Vibrational spectroscopy enables aspects on the molecular structure of kulanite to be assessed.
Molecular structure of the phosphate mineral koninckite - a vibrational spectroscopic study
We have undertaken a study of the mineral koninckite from
Litosice (Czech Republic), a hydrated ferric phosphate, using a
combination of scanning electron microscopy with electron probe
micro-analyzer (wavelength-dispersive spectroscopy) and
vibrational spectroscopy. Chemical analysis shows that studied
koninckite is a pure phase with an empirical formula Fe3+
(0.99)(PO4)(1.00) center dot 2.75 H2O, with minor enrichment in
Al, Ca, Ti, Si, Zn, and K (averages 0.00X apfu). Raman bands
and shoulders at 3495, 3312, 3120, and 2966 cm(-1) and infrared
bands and shoulders at 3729, 3493, 3356, 3250, 3088, 2907, and
2706 cm(-1) are assigned to the nu OH stretching of
structurally distinct differently hydrogen bonded water
molecules, A Raman band at 1602 cm(-1) and shoulders at 1679,
1659, 1634, and 1617 cm(-1) and infrared bands at 1650 and 1598
cm(-1) are assigned to the nu(2)(delta) H2O bending vibrations
of structurally distinct differently hydrogen bonded water
molecules. Raman shoulders at 1576, 1554, 1541, 1532, and 1520
cm(-1) and infrared shoulders at 1541 and 1454 cm(-1) may be
probably connected with zeolitically bonded water molecules
located in the channels. Raman bands and shoulders at 1148,
1132, 1108, 1063, 1048, and 1015 cm(-1) and an infrared band
and shoulders at 1131, 1097, 1049, and 1017 cm(-1) are assigned
to the nu(3) PO43- triply degenerate antisymmetric stretching
vibrations. A Raman band and a shoulder at 994 and 970 cm(-1),
respectively, and an infrared band and a shoulder at 978 and
949 cm(-1), respectively, are assigned to the nu(1) PO43-
symmetric stretching vibrations. Infrared shoulders at 873,
833, and 748 cm(-1) are assigned to libration modes of water
molecules. Raman bands and shoulders at 670, 648, 631, 614,
600, 572, and 546 cm(-1) and infrared bands at 592 and 534
cm(-1) are assigned to the nu(4) (delta) PO(4)(3-)triply
degenerate out-of-plane bending vibrations; weak band at 570
cm(-1) may coincide with the delta Fe-O bending vibration.
Raman bands and shoulders at 453, 443, 419, and 400 cm(-1) are
assigned to the nu(2) (delta) PO43- doubly degenerate in-plane
bending vibrations. Raman bands at 385, 346, 324, 309, 275,
252, and 227 cm(-1) are assigned to the nu Fe-O stretching
vibrations in FeO6 octahedra. Raman bands at 188, 158, 140,
112, 89, and 73 cm(-1) are assigned to lattice vibrations.
Synthesis of 2,4-dideoxy-.beta.-D-erythro-hexopyranosyl nucleosides
The synthesis of 1-(2,4-dideoxy-β-D-erythro-hexopyranosyl)thymine (12) 1 was accomplished using two different synthetic routes. It was obtained starting either from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose or from tri-O-acetyl-D-glucal. The other modified nucleosides, with either a cytosine, guanine, or adenine moiety, were synthesized using the second reaction scheme. Deoxygenation reactions were accomplished with the (2,4-dichlorophenoxy)thiocarbonyl derivatives generated in situ