Variation of Spirulina maxima biomass production in different depths of urea-used culture medium.

Fewer studies have assessed the outdoor cultivation of Spirulina maxima compared with S. platensis, although the protein content of S. maxima is higher than S. platensis. Spirulina growth medium requires an increased amount of NaHCO3, Na2CO3, and NaNO3, which increases the production cost. Therefore, the current study used a low-cost but high-efficiency biomass production medium (Medium M-19) after testing 33 different media. The medium depth of 25 cm (group A) was sub-divided into A1 (50% cover with a black curtain (PolyMax, 12 oz ultra-blackout), A2 (25% cover), and A3 (no cover). Similarly the medium depths of 30 and 35 cm were categorized as groups B (B1, B2, and B3) and C (C1, C2, and C3), respectively, and the effects of depth and surface light availability on growth and biomass production were assessed. The highest biomass production was 2.05 g L-1 in group A2, which was significantly higher (p < 0.05) than that in all other groups and sub-groups. Spirulina maxima died in B1 and C1 on the fifth day of culture. The biochemical composition of the biomass obtained from A2 cultures, including protein, carbohydrate, lipid, moisture, and ash, was 56.59%, 14.42%, 0.94%, 5.03%, and 23.02%, respectively. Therefore, S. maxima could be grown outdoors with the highest efficiency in urea-enriched medium at a 25-cm medium depth with 25% surface cover or uncovered.

Variation of Spirulina maxima biomass production in different depths of urea-used culture medium

Fewer studies have assessed the outdoor cultivation of Spirulina maxima compared with S. platensis, although the protein content of S. maxima is higher than S. platensis. Spirulina growth medium requires an increased amount of NaHCO3, Na2CO3, and NaNO3, which increases the production cost. Therefore, the current study used a low-cost but high-efficiency biomass production medium (Medium M-19) after testing 33 different media. The medium depth of 25 cm (group A) was sub-divided into A1 (50% cover with a black curtain (PolyMax, 12 oz ultra-blackout), A2 (25% cover), and A3 (no cover). Similarly the medium depths of 30 and 35 cm were categorized as groups B (B1, B2, and B3) and C (C1, C2, and C3), respectively, and the effects of depth and surface light availability on growth and biomass production were assessed. The highest biomass production was 2.05 g L-1 in group A2, which was significantly higher (p < 0.05) than that in all other groups and sub-groups. Spirulina maxima died in B1 and C1 on the fifth day of culture. The biochemical composition of the biomass obtained from A2 cultures, including protein, carbohydrate, lipid, moisture, and ash, was 56.59%, 14.42%, 0.94%, 5.03%, and 23.02%, respectively. Therefore, S. maxima could be grown outdoors with the highest efficiency in urea-enriched medium at a 25-cm medium depth with 25% surface cover or uncovered.

Morphological, Molecular, and Biochemical Characterization of Monounsaturated Fatty Acids-Rich Chlamydomonas sp. KIOST-1 Isolated from Korea.

Microalgae hold promise as producers of sustainable biomass for the production of biofuels and other biomaterials. However, the selection of strains with efficient and robust production of desirable resources remains challenging. In this study, we isolated a green microalga from Korea and analyzed its morphological, molecular, and biochemical characteristics. Microscopic and phylogenetic analyses demonstrated that the isolate could be classified into the genus Chlamydomonas, and we designated the isolate Chlamydomonas s p. K IOST -1. Compositions of protein, lipid, and carbohydrate in the microalgal cells were estimated to be 58.8 ± 0.2%, 22.7 ± 1.2%, and 18.5 ± 1.0%, respectively. Similar to other microalgae belonging to Chlorophyceae, the dominant amino acid and monosaccharide in Chlamydomonas sp. KIOST-1 were glutamic acid and glucose. On the other hand, the proportions of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids clearly differed from other species in the genus Chlamydomonas, and monounsaturated fatty acids accounted for a large portion (41.3%) of the total fatty acids in the isolate. Based on these results, Chlamydomonas sp. KIOST-1 has advantageous characteristics for biomass production.

2-[(1,3-Benzo-thia-zol-2-yl)imino-meth-yl]-6-meth-oxy-phenol: a new monoclinic polymorph.

The title compound, C15H12N2O2S, is a P21/c polymorph of a previously reported P21/n polymorph [Büyükgüngör et al. (2004 ▶). Acta Cryst. E60, o1414-o1416]. The dihedral angle between the benzo-thia-zole (r.m.s. deviation = 0.010 Å) and the benzene ring of 7.86 (6)° compares with 10.76 (10)° in the literature structure. The meth-oxy substituent is almost coplanar with the benzene ring to which it is attached [C-O-C-C torsion angle = 178.31 (14)°] and the conformation about the imine bond [1.287 (2) Å] is E. There is an intra-molecular O-H⋯N hydrogen bond and the hy-droxy O and thio-ether S atoms are syn. In the crystal, columns are formed along the b axis as centrosymmetric dimeric aggregates, mediated by C-H⋯O inter-actions and linked by π-π inter-actions between the thia-zole and benzene rings [centroid-to-centroid distance = 3.8256 (10) Å].

n-Butyldichlorido{4-cyclo-hexyl-1-[1-(pyridin-2-yl-κN)ethyl-idene]thio-semi-carb-azi-dato-κ²N¹,S}tin(IV).

Two independent mol-ecules comprise the asymmetric unit in the title compound, [Sn(C4H9)(C14H19N4S)Cl2]. In each mol-ecule, the Sn(IV) atom exists within a distorted octa-hedral geometry defined by the N,N',S-tridentate mono-deprotonated Schiff base ligand, two mutually trans Cl atoms, and the α-C atom of the n-butyl group; the latter is trans to the azo-N atom. The greatest distortion from the ideal geometry is found in the nominally trans angle formed by the S and pyridyl-N atoms at Sn [151.72 (7) and 152.04 (7)°, respectively]. In the crystal, mol-ecules are consolidated into a three-dimensional architecture by a combination of N-H⋯Cl, C-H⋯π and π-π inter-actions [inter-centroid distances = 3.6718 (19) and 3.675 (2) Å].

Chlorido{4-cyclo-hexyl-1-[1-(pyridin-2-yl-κN)ethyl-idene]thio-semicarbazidato-κ(2)N(1),S}diphenyl-tin(IV).

The distorted octa-hedral geometry about the Sn(IV) atom in the title compound, [Sn(C(6)H(5))(2)(C(14)H(19)N(4)S)Cl], is defined by the N,N,S-tridentate Schiff base ligand, two mutually trans ipso-C atoms of the Sn-bound phenyl groups, and the Cl atom which is trans to the azo N atom. The two five-membered chelate rings and pyridyl ring are almost coplanar with the dihedral angle between the outer five-membered chelate and pyridine rings being 5.39 (8)°. Centrosymmetric dimers feature in the crystal packing mediated by N-H⋯S hydrogen bonds, leading to eight-membered {⋯HNCS}(2) synthons. The dimeric aggregates are connected into a three-dimensional architecture by C-H⋯Cl and C-H⋯π inter-actions, as well as π-π inter-actions occurring between centrosymmetrically related pyridine rings [centroid-centroid distance = 3.6322 (13) Å].

{4-Hy-droxy-N'-[(2E,3Z)-4-oxido-4-phenyl-but-3-en-2-yl-idene]benzo-hydra-zidato}diphenyl-tin(IV) methanol monosolvate.

Two independent diphenyl-tin mol-ecules and two independent methanol mol-ecules comprise the asymmetric unit of the title compound, [Sn(C(6)H(5))(2)(C(17)H(14)N(2)O(3))]·CH(3)OH. The Sn atom in each is five-coordinated by a tridentate ligand and the ipso-C atoms of the Sn-bound benzene substituents. The resulting C(2)N(2)O donor set defines a coordination geometry that is inter-mediate between trigonal-bipyramidal (TP) and square-pyramidal (SP), with one mol-ecule slightly tending towards TP and the other slightly towards SP. The mol-ecules differ in terms of the relative orientations of the terminal benzene rings [dihedral angles = 45.71 (18) and 53.98 (17)°] and of the Sn-bound benzene substituents [dihedral angles = 59.5 (2) and 45.77 (18)°, respectively]. The most prominent feature of the crystal packing is the formation of four-mol-ecule aggregates via O-H⋯O and O-H⋯N hydrogen bonds, in which the hy-droxy group is connected to a methanol mol-ecule which, in turn, is linked to a non-coordinating N atom. Weak C-H⋯π inter-actions also occur.

{4-Hy-droxy-N'-[(2E,3Z)-4-oxido-4-phenyl-but-3-en-2-yl-idene]benzo-hydrazidato}dimethyl-tin(IV).

The Sn(IV) atom in the title compound, [Sn(CH(3))(2)(C(17)H(14)N(2)O(3))], is five-coordinated within a C(2)N(2)O donor set provided by the N,N,O-tridentate ligand and two methyl groups. The resultant coordination geometry is inter-mediate between trigonal-bipyramidal and square-pyramidal. In the crystal, supra-molecular zigzag chains propagating along the c- axis direction are mediated by O-H⋯O hydrogen bonds, and weak C-H⋯π inter-actions consolidate the packing.

1-Cyclo-hexyl-3-{(E)-[1-(pyridin-2-yl)ethyl-idene]amino}-thio-urea.

In the title thio-urea derivative, C(14)H(20)N(4)S, the non-ring non-H atoms are approximately planar, with an r.m.s. deviation of 0.0720 Å. The pyridine ring is twisted out of this plane and makes a dihedral angle of 16.85 (13)° with it. The mean plane passing through the cyclo-hexyl ring is almost normal to the central plane [dihedral angle = 69.23 (8)°]. An intra-molecular N-H⋯N(imine) hydrogen bond occurs. Centrosymmetric dimers are formed in the crystal structure via pairs of N-H⋯S hydrogen bonds, and these are connected into a supra-molecular chain along the a axis via C-H⋯π(pyrid-yl) inter-actions.

(2E)-2-(2-Phenyl-hydrazin-1-yl-idene)propanoic acid.

The 13 non-H atoms comprising the title compound, C(9)H(10)N(2)O(2), are close to planar (r.m.s. deviation = 0.140 Å), with maximum deviations of 0.292 (1) and 0.210 (1) Što either side of the least-squares plane exhibited by the hy-droxy and carbonyl O atoms, respectively. The observed conformation is stabilized by an intra-molecular O-H⋯N hydrogen bond. The conformation about the N=C double bond [1.2909 (16) Å] is E. The hy-droxy OH group also forms an inter-molecular hydrogen bond to a carbonyl O atom, and the amine H atom similarly forms an N-H⋯O hydrogen bond to a second carbonyl O atom. The result is the formation of a double layer with a flat topology. Layers stack along the a-axis direction connected by C-H⋯π inter-actions.

3-{(E)-[1-(2-Hy-droxy-phen-yl)ethyl-idene]amino}-1-(2-methyl-phen-yl)thio-urea.

In the title thio-urea derivative, C(16)H(17)N(3)OS, the hy-droxy- and methyl-substituted benzene rings form dihedral angles of 9.62 (12) and 55.69 (6)°, respectively, with the central CN(3)S chromophore (r.m.s. deviation = 0.0117 Å). An intra-molecular O-H⋯N hydrogen bond ensures the coplanarity of the central atoms. The H atoms of the NH groups are syn and the conformation about the N=C double bond [1.295 (4) Å] is E. In the crystal, helical supra-molecular chains sustained primarily by N-H⋯S hydrogen bonds are found. Additional stabilization is provided by C-H⋯π and π-π [ring centroid(hy-droxy-benzene)⋯ring centroid(methyl-benzene) = 3.8524 (18) Å] inter-actions.

(2E)-2-[2-(Cyclo-hexyl-carbamothio-yl)hydrazinylidene]-propanoic acid.

In the title thio-urea derivative, C(10)H(17)N(3)O(2)S, the carboxyl group and the least-squares plane through the cyclo-hexyl ring are twisted out of the plane through the central CN(3)S residue; the respective dihedral angles are 7.18 (8) and 62.29 (4)°. The conformation about the azomethine bond [1.275 (2) Å] is E. The NH groups are anti, with one forming an intra-molecular N-H⋯N hydrogen bond. The main feature of the crystal structure is the formation of linear supra-molecular chains along [110] mediated by alternating pairs of O-H⋯O and pairs of N-H⋯S hydrogen bonds.

Dichlorido{4-cyclo-hexyl-1-[1-(2-pyridyl-κN)ethyl-idene]thio-semicarbazidato-κN,S}methyl-tin(IV).

The monodeprotonated Schiff base ligand in the title compound, [Sn(CH(3))(C(14)H(19)N(4)S)Cl(2)], N,N',S-chelates to the Sn atom, which is six-coordinated in an octa-hedral environment. The three coordinating atoms along with the methyl C atom comprise a square plane, above and below which are positioned the Cl atoms. The amino group is a hydrogen-bond donor to a Cl atom of an adjacent mol-ecule, the hydrogen bond giving rise to a helical chain extending parallel to [100].

n-Butyl-dichlorido{4-cyclo-hexyl-1-[phenyl(2-pyridyl-κN)methyl-ene]-thiosemicarbazidato-κN,S}tin(IV) chloro-form monosolvate.

The monodeprotonated Schiff base ligand in the title com-pound, [Sn(C(4)H(9))(C(19)H(21)N(4)S)Cl(2)]·CHCl(3), N,N',S-chelates to the Sn atom, which is six-coordinated in an octa-hedral environment. The three coordinating atoms along with the butyl C atom comprise a square plane, above and below which are positioned the Cl atoms. The amino group is a hydrogen-bond donor to a Cl atom of an adjacent mol-ecule, the hydrogen bond giving rise to a helical chain propagating in [010]. The Cl and H atoms of the chloro-form mol-ecule are disordered over two positions in an 0.67:0.33 ratio.

Di-n-but-yl{4-hydr-oxy-N'-[(2-oxido-1-naphthyl-κO)methyl-ene]benzo-hydrazidato-κO,N'}tin(IV).

The deprotonated Schiff base ligand in the title compound, [Sn(C(4)H(9))(2)(C(18)H(12)N(2)O(3))], O,N,O'-chelates to the Sn atom, which is five-coordinated in a cis-C(2)NO(2)Sn trigonal-bipyramidal environment. The apical sites are occupied by the O atoms [O-Sn-O = 155.2 (2)°]. The hydr-oxy group is a hydrogen-bond donor to the two-coordinate N atom of an adjacent mol-ecule, the hydrogen-bonding inter-action giving rise to a helical chain running along the c axis. The carbon atoms of the butyl chains are equally disordered over two positions.

Di-n-but-yl{1-[1-(2-hydroxy-phen-yl)ethyl-idene]-5-[1-(2-oxidophen-yl)ethyl-idene]thio-carbazonato-κO,N,S}tin(IV).

The 'symmetrical' 1,5-bis-[1-(2-hydroxy-phen-yl)ethyl-idene]thio-carbazone Schiff base condenses with dibutyl-tin oxide to form the title complex, [Sn(C(4)H(9))(2)(C(17)H(16)N(4)O(2)S)], in which the deprotonated ligand O,N,S-chelates to the Sn atom of two crystallographically independent mol-ecules. The ligand bears a formal negative charge on the S and one O atom; the other O atom retains its H atom. The Sn atoms are five-coordinated in a cis-C(2)NOSSn trigonal-bipyramidal environment, and the apical sites are occupied by the O and S atoms. In both mol-ecules, the hydr-oxy group is hydrogen bonded to a double-bonded N atom, generating a six-membered ring. The amino group is a donor to the coordinated O atom of an adjacent mol-ecule, the hydrogen-bonding inter-action giving rise to a helical chain running along the b axis. In one of the independent mol-ecules, the atoms of one of the n-butyl groups are disordered over two sets of sites with equal occupancy. In the other independent mol-ecule, the atoms of both n-butyl groups are disordered over two sets of sites with equal occupancy and, in addition, the Sn and S atoms were also refined as disordered over two sets of sites with equal occupancy.

1,5-Bis[(E)-1-(2-hydroxyphenyl)ethyl-idene]thiocarbonohydrazide mono-hydrate.

In the title compound, C(17)H(18)N(4)O(2)S·H(2)O, the thio-urea derivative is almost planar, with an r.m.s. deviation for the non-H atoms of 0.057 Å. The hydroxyl groups lie to the same side of the mol-ecule as the thione S atom, a conformation that allows the formation of intra-molecular O-H⋯S and O-H⋯N hydrogen bonds. In the crystal structure, the thio-urea and water mol-ecules self-assemble into a two-dimensional array by a combination of O(water)-H⋯O(hydrox-yl), N-H⋯O(water) and O(water)-H⋯S hydrogen bonds and C-H⋯π inter-actions.

{4-Hy-droxy-N'-[(2-oxido-1-naphthyl-κO)methyl-idene]benzohydrazidato-κN',O}dimethyl-tin(IV).

Two independent but very similar mol-ecules comprise the asymmetric unit of the title compound, [Sn(CH(3))(2)(C(18)H(12)N(2)O(3))]. Each Sn atom is coordinated by two methyl groups and two O atoms and an N atom from the dinegative tridentate ligand. The resultant C(2)NO(2) donor set defines a coordination geometry inter-mediate between square-pyramidal and trigonal-pyramidal, with a small tendency towards the former. Zigzag chains running along the a axis mediated by O-H⋯N hydrogen bonding characterize the crystal packing. These are connected into layers in the ab plane by a combination of C-H⋯N and π-π [centroid-centroid distances = 3.658 (2) and 3.6740 (18) Å] inter-actions. The layers are connected along the c axis via C-H⋯O inter-actions.

Aqua-chlorido{2-[2-(cyclo-hexyl-carbamo-thioyl-κS)hydrazinyl-idene-κN]propano-ato(2-)}phenyl-tin(IV).

In the title organotin compound, [Sn(C(6)H(5))(C(10)H(15)N(3)O(2)S)Cl(H(2)O)], the Sn atom is coordinated by the S, O, and imine N atoms of the dinegative tridentate ligand, a chloride ligand, the ipso-C atom of a phenyl ligand and by a water mol-ecule in a distorted octa-hedral coordination environment. Coordin-ated water mol-ecules link the organotin mol-ecules by forming O-H⋯O hydrogen bonds with both carbonyl and carboxyl-ate O atoms, leading to 12-membered {⋯OCO⋯HOH⋯}(2) synthons. This results in the formation of supra-molecular chains along the c axis. The chains pack in the ac plane and stack along the b axis with links between layers afforded by N-H⋯Cl hydrogen bonds.

n-Butyl-dichlorido(2-{(1E)-1-[2-(pyridin-2-yl)hydrazin-1-yl-idene]eth-yl}phenolato)tin(IV).

Two independent mol-ecules comprise the asymmetric unit of the title compound, [Sn(C(4)H(9))(C(13)H(12)N(3)O)Cl(2)]. The Sn atom in each is coordinated by the tridentate ligand via the phenoxide O, hydrazine N and pyridyl N atoms, forming five- and six-membered chelate rings. The approximately octa-hedral coordination geometry is completed by the α-C atom of the n-butyl group (which is trans to the hydrazine N atom) and two mutually trans Cl atoms. Differences between the mol-ecules are evident in the relative planarity of the chelate rings and in the conformations of the n-butyl groups [C-C-C-C = 177.2 (5) and -64.4 (11)°]. Significant differences in the Sn-Cl bond lengths are related to the formation of N-H⋯Cl hydrogen bonds, which link the mol-ecules comprising the asymmetric unit into dimeric aggregates. These are consolidated in the crystal packing by C-H⋯Cl contacts. The structure was refined as an inversion twin; the minor twin component is 37 (3)%.